Opinion by Judge WILLIAM A. FLETCHER; Dissent by Judge TROTT.
OPINION
W. FLETCHER, Circuit Judge:
Plaintiff Dion Starr brings a § 1983 action for damages resulting from a violent attack he allegedly suffered while he was an inmate in the Los Angeles County Jail. The district court dismissed Starr’s supervisory liability claim for deliberate indifference against Sheriff Leroy Baca in his individual capacity under Federal Rule of Civil Procedure 12(b)(6) for failure to state a claim. Because we hold that Starr has adequately stated a claim, we reverse and remand for further proceedings.
I. Background
Because we are reviewing an order granting a motion to dismiss under Rule 12(b)(6), we take the facts alleged in the complaint to be true. Navarro v. Block, 250 F.3d 729, 732 (9th Cir.2001). Starr’s Third Amended Complaint alleges that on or about January 27, 2006, he was in custody in the Los Angeles County Jail. A group of inmates gathered at his cell door and threatened to inflict physical harm on him. He yelled for the deputies guarding the jail to come to his aid. Instead of protecting him, a deputy opened Starr’s cell gate in order to allow the group of inmates to enter. The inmates entered the cell and repeatedly stabbed Starr and his cellmate with knife-like objects. They stabbed Starr twenty-three times while Starr screamed for help and protection. After the attacking inmates left the cell, several deputies went to Starr. Starr lay on the floor of his cell, seriously injured, bleeding and moaning in pain. One deputy yelled at him, “nigger lay down.” While repeatedly yelling “shut up nigger,” the deputy then kicked his face, nose, and body numerous times, causing pain, bleeding and a nose fracture. Other deputies stood by and watched. The deputy who kicked Starr subsequently interfered with his ability to obtain medical treatment for his injuries. Starr continues to suffer [1194]*1194from and receive treatment for his injuries.
Starr sued Sheriff Baca as well as the deputies directly involved in the attack. His claims against the deputies are not at issue in this appeal. In his claim against Sheriff Baca, Starr alleges unconstitutional conditions of confinement in violation of the Eighth and Fourteenth Amendments. He alleges that Sheriff Baca is liable in his individual capacity because he knew or should have known about the dangers in the Los Angeles County Jail, and that he was deliberately indifferent to those dangers.
After giving Starr several chances to plead his claim against Sheriff Baca, the district court dismissed the claim with prejudice under Rule 12(b)(6). The district court held that Starr’s allegations against Sheriff Baca were insufficient to state a claim for supervisory liability because the complaint’s recital of prior incidents and accompanying allegations did not sufficiently state a causal connection between Sheriff Baca’s action and inaction and the alleged injury to Starr. The district court wrote that Starr “does not allege that Baca himself directly participated in any way in the January 27, 2006 incident or that he was involved in any review or investigation of it.” Nor, the district court held, did Starr allege any specific policy implemented by Sheriff Baca that caused the violation.
The district court directed that final judgment in favor of Sheriff Baca be entered under Federal Rule of Civil Procedure 54(b). Starr appeals.
II. Standard of Review
We review de novo a district court’s dismissal of a complaint under Fed.R.Civ.P. 12(b)(6) for failure to state a claim. Caviness v. Horizon Cmty. Learning Ctr., Inc., 590 F.3d 806, 811-12 (9th Cir.2010).
III. Discussion
To prevail on his claim under the Eighth and Fourteenth Amendments, Starr must demonstrate “either that prison officials acted with ‘deliberate indifference’ or that their conduct was so reckless as to be tantamount to a desire to inflict harm.” Redman v. Cnty. of San Diego, 942 F.2d 1435, 1449 (9th Cir.1991). The gravamen of Starr’s claim against Sheriff Baca is deliberate indifference.
On appeal, Starr contends that the district court erred in dismissing his claim against Sheriff Baca on the pleadings. Sheriff Baca contends that the Supreme Court eliminated claims for supervisory liability in its decision in Iqbal. He contends further that even under pre-Iqbal case law, Starr has not alleged a causal connection between Sheriff Baca’s conduct and his injury. Finally, he contends that Starr has failed to allege anything more than legal conclusions, rendering the complaint insufficient under Federal Rule of Civil Procedure 8(a), as interpreted by Iqbal.
Because the question of whether Iqbal eliminated supervisory liability was not adequately briefed, we ordered supplemental briefing after oral argument. Having reviewed the original and supplemental briefing, we now address the parties’ arguments.
A. Supervisory Liability after Ashcroft v. Iqbal
We have long permitted plaintiffs to hold supervisors individually liable in § 1983 suits when culpable action, or inaction, is directly attributed to them. We have never required a plaintiff seeking to state a claim for supervisory liability to allege that a supervisor was physically present when the injury occurred. In Larez v. City of Los Angeles, 946 F.2d 630 (9th Cir.1991), we explained that to be held [1195]*1195liable, the supervisor need not be “directly and personally involved in the same way as are the individual officers who are on the scene inflicting constitutional injury.” Id. at 645. Rather, the supervisor’s participation could include his “own culpable action or inaction in the training, supervision, or control of his subordinates,” “his acquiescence in the constitutional deprivations of which the complaint is made,” or “conduct that showed a reckless or callous indifference to the rights of others.” Id. at 646 (internal citations, quotation marks, and alterations omitted).
After the district court dismissed Starr’s claim, but before briefing on appeal, the Supreme Court decided Ashcroft v. Iqbal, - U.S. -, 129 S.Ct. 1937, 173 L.Ed.2d 868 (2009). Plaintiff Iqbal, a Pakistani Muslim, had been arrested and detained in severely restrictive conditions following the attacks of September 11, 2001. Id. at 1943. He filed a Bivens action in federal court against his jailers and various officials, including Attorney General John Ashcroft and F.B.I. Director Robert Mueller, alleging purposeful discrimination on the basis of race, religion and national origin. Id. (citing Bivens v. Six Unknown Fed. Narcotics Agents, 403 U.S. 388, 91 S.Ct. 1999, 29 L.Ed.2d 619 (1971)). A Bivens action seeks to hold federal officers individually liable for constitutional violations. Although “more limited in some respects,” a Bivens action is the federal analog to an action against state or local officials under § 1983. Hartman v. Moore, 547 U.S. 250, 254 n. 2, 126 S.Ct. 1695, 164 L.Ed.2d 441 (2006).
The Court held that Iqbal’s complaint failed to plead facts sufficient to state a claim against Attorney General Ashcroft and Director Mueller for purposeful and unlawful discrimination. Iqbal, 129 S.Ct. at 1954. The Court explained that because Bivens and § 1983 suits do not allow for the imposition of vicarious liability, stating a claim against a government official in his or her individual capacity for purposeful discrimination requires pleading that “each Government-official defendant, through the official’s own individual actions, has violated the Constitution.” Id. at 1948.
The Court stated that “[t]he factors necessary to establish a Bivens violation will vary with the constitutional provision at issue.” Id. The Court explained that purposeful discrimination, which was alleged against Attorney General Ashcroft and Director Mueller, requires a plaintiff to “plead and prove that the defendant acted with discriminatory purpose.” Id. Proving purposeful discrimination requires showing “more than intent as volition or intent as awareness of consequences”; the plaintiff must show that the decisionmaker acted because of his action’s adverse effects, not merely in spite of them. Id. (internal quotation marks omitted). Therefore, the supervisors in Iqbal needed to have “adopted and implemented the detention policies at issue not for a neutral, investigative reason but for the purpose of discriminating on account of race, religion, or national origin.” Id. at 1948-49. Holding Attorney General Ashcroft and Director Mueller personally liable for unconstitutional discrimination if they did not themselves have a discriminatory purpose would be equivalent to finding them vicariously liable for their subordinates’ violation, which Bivens and § 1983 do not allow. In so holding, Iqbal followed earlier cases holding that alleging a supervisor’s mere awareness of the discriminatory effects of his or her actions or inaction does not state a claim of unconstitutional discrimination.
Starr does not allege purposeful discrimination by Sheriff Baca. Rather, he alleges unconstitutional conditions of confinement in violation of the Eighth Amendment’s prohibition against cruel and unusual punishment, as incorporated through [1196]*1196the Due Process Clause of the Fourteenth Amendment. A claim of unconstitutional conditions of confinement, unlike a claim of unconstitutional discrimination, is actionable on a theory of deliberate indifference. See Farmer v. Brennan, 511 U.S. 825, 114 S.Ct. 1970, 128 L.Ed.2d 811 (1994). A showing that a supervisor acted, or failed to act, in a manner that was deliberately indifferent to an inmate’s Eighth Amendment rights is sufficient to demonstrate the involvement — and the liability — of that supervisor. Thus, when a supervisor is found liable based on deliberate indifference, the supervisor is being held liable for his or her own culpable action or inaction, not held vicariously liable for the culpable action or inaction of his or her subordinates.
We see nothing in Iqbal that indicates that the Supreme Court intended to overturn longstanding case law on deliberate indifference claims against supervisors in conditions of confinement cases. We also note that, to the extent that our sister circuits have confronted this question, they have agreed with our interpretation of Iqbal. See Dodds v. Richardson, 614 F.3d 1185, 1204 (10th Cir.2010) (“We therefore conclude that after Iqbal, Plaintiff can no longer succeed on a § 1983 claim against Defendant by showing that as a supervisor he behaved knowingly or with deliberate indifference that a constitutional violation would occur at the hands of his subordinates, unless that is the same state of mind required for the constitutional deprivation he alleges.” (emphasis added; internal quotation marks omitted)); Sandra T.E. v. Grindle, 599 F.3d 583, 591 (7th Cir.2010) (Iqbal does not change the fact that “[w]hen a state actor’s deliberate indifference deprives someone of his or her protected liberty interest in bodily integrity, that actor violates the Constitution, regardless of whether the actor is a supervisor or subordinate, and the actor may be held liable for the resulting harm.”); Sanchez v. Pereira-Castillo, 590 F.3d 31, 49 (1st Cir.2009) (“Although ‘Government officials may not be held liable for the unconstitutional conduct of their subordinates under a theory of respondeat superior,’ supervisory officials may be liable on the basis of their own acts or omissions,” including supervising “with deliberate indifference toward the possibility that deficient performance of the task may contribute to a civil rights deprivation.” (quoting Iqbal, 129 S.Ct. at 1948) (some internal quotation marks omitted)).
We therefore conclude that where the applicable constitutional standard is deliberate indifference, a plaintiff may state a claim for supervisory liability based upon the supervisor’s knowledge of and acquiescence in unconstitutional conduct by others.
B. Supervisory Liability for Deliberate Indifference
Sheriff Baca contends that even under a deliberate indifference standard Starr has failed to state a claim for supervisory liability. He contends that Starr’s claim fails for want of a causal connection between Sheriff Baca’s allegedly wrongful action and inaction and Starr’s alleged injury. We disagree.
A defendant may be held liable as a supervisor under § 1983 “if there exists either (1) his or her personal involvement in the constitutional deprivation, or (2) a sufficient causal connection between the supervisor’s wrongful conduct and the constitutional violation.” Hansen v. Black, 885 F.2d 642, 646 (9th Cir.1989). “[A] plaintiff must show the supervisor breached a duty to plaintiff which was the proximate cause of the injury. The law clearly allows actions against supervisors under section 1983 as long as a sufficient causal connection is present and the plaintiff was [1197]*1197deprived under color of law of a federally-secured right.” Redman, 942 F.2d at 1447 (internal quotation marks omitted).
“The requisite causal connection can be established ... by setting in motion a series of acts by others,” id. (alteration in original; internal quotation marks omitted), or by “knowingly refus[ing] to terminate a series of acts by others, which [the supervisor] knew or reasonably should have known would cause others to inflict a constitutional injury,” Dubner v. City & Cnty. of San Francisco, 266 F.3d 959, 968 (9th Cir.2001). “A supervisor can be liable in his individual capacity for his own culpable action or inaction in the training, supervision, or control of his subordinates; for his acquiescence in the constitutional deprivation; or for conduct that showed a reckless or callous indifference to the rights of others.” Watkins v. City of Oakland, 145 F.3d 1087, 1093 (9th Cir.1998) (internal alteration and quotation marks omitted).
Our decision in Redman is illustrative. In Redman, the plaintiff alleged that the facility in which he was confined was overcrowded; that the Sheriff knew the facility was not a proper place to detain him and posed a risk of harm but had placed him there anyway; and that the Sheriff was ultimately in charge of the facility’s operations. 942 F.2d at 1446-47. Reversing the district court’s grant of a directed verdict in favor of the Sheriff, we concluded that a reasonable jury could have found that the Sheriff was deliberately indifferent to the plaintiffs safety. Id. at 1447-48. Such a jury could have found that the Sheriff “knew or reasonably should have known of the overcrowding” and that “he acquiesced in a deficient policy that was a moving force behind” the harm caused to the plaintiff. Id. at 1447.
Starr alleges that Sheriff Baca’s knowledge of the unconstitutional conditions in the jail, including his knowledge of the culpable actions of his subordinates, coupled with his inaction, amounted to acquiescence in the unconstitutional conduct of his subordinates. As we noted in Red-man, under California law, “[t]he sheriff is required by statute to take charge of and keep the county jail and the prisoners in it, and is answerable for the prisoner’s safekeeping.” Id. at 1446 (citing Cal. Gov. Code §§ 26605, 26610; Cal.Penal Code § 4006). We have held that “acquiescence or culpable indifference” may suffice to show that a supervisor “personally played a role in the alleged constitutional violations.” Menotti v. City of Seattle, 409 F.3d 1113, 1149 (9th Cir.2005); see Redman, 942 F.2d at 1446. Starr’s allegations that the actions or inactions of the person “answerable for the prisoner’s safekeeping” caused his injury are therefore sufficient to state a claim of supervisory liability for deliberate indifference.
C. Adequacy of Starr’s Complaint Under Rule 8(a)
Finally, Sheriff Baca argues that even if Starr’s complaint might be read to state a claim of deliberate indifference, it does not satisfy the pleading standard that the Court in Iqbal held Federal Rule of Civil Procedure 8(a) to require. Our dissenting colleague agrees with the district court that Starr has not satisfied the pleading requirements of Rule 8(a), as interpreted by Iqbal. He writes, “Plaintiffs complaint does nothing more than allege raw legal conclusions with insufficient facts to support them.” Diss. Op. at 1205. We disagree.
1. Allegations of the Complaint
Starr claims that Sheriff Baca failed to act to protect inmates under his care despite his knowledge that they were in danger because of culpable acts of his subordinates and despite his ability to [1198]*1198take actions that would have protected them. That is, to use language from our prior opinions, Starr claims that Sheriff Baca “knowingly refused to terminate a series of acts by others, which he knew or reasonably should have known would cause ... constitutional injury.” Dubner, 266 F.3d at 968. Or, to state it slightly differently, Starr claims that Sheriff Baca is “liable in his individual capacity for his own culpable action or inaction in the training, supervision, or control of his subordinates!.]” Watkins, 145 F.3d at 1093 (emphasis added; internal quotation marks omitted).
It is somewhat tedious to recount the many allegations in the complaint detailing what Sheriff Baca knew or should have known, and what Sheriff Baca did or failed to do. But given our colleague’s conclusion that Starr’s complaint has not satisfied Rule 8(a), we feel obliged to do so.
In paragraph 36, Starr alleges that the United States Department of Justice (“DOJ”) initiated an investigation into conditions at Los Angeles County Jails in June 1996. On September 5, 1997, the DOJ “gave BACA, then a supervisor, clear written notice in a ‘findings letter’ of a continued and serious pattern and practices of constitutional violations including! ] abuse of inmates by sheriffs deputies working in the jail and inmate on inmate violence.”
In paragraph 37, Starr alleges that Sheriff Baca receives “weekly reports from his subordinates responsible for reporting-deaths and injuries in the jails,” and receives “ongoing reports of his Special Counsel and Office of Independent Review.”
In paragraph 38, Starr alleges that in 1999, “under threat of a lawsuit by the DOJ, BACA and the COUNTY submitted to a Memorandum of Understanding (“MOU”) with the DOJ which required BACA and the COUNTY to address and correct the continuous constitutional violations to which inmates were being subjected, particularly inmates suffering from mental problems. BACA personally signed the MOU. However, after years of monitoring the County Jail system, under the authority of the MOU, in 2006, the DOJ experts issued a report which still found noncompliance with many of its recommendations regarding the abuse of inmates and the deficiencies which continue at county jails[.]”
In paragraph 39, Starr alleges that on July 6, 2002, “Ramon Gavira was severely beaten by a female deputy and later ... was killed in his cell at [the] county jail. Deputies and staff testified that they were not investigated nor disciplined for lapses in supervision of Mr. Gavira and allegations that Mr. Gavira had been physically abused by deputies. BACA was personally advised of the failure to investigate and no discipline being imposed!.]”
In paragraph 40, Starr alleges that on March 23, 2003, “BACA was ... again made aware of Hispanic inmate gangs attacking African Americans and the failure to provide reasonable security when the COUNTY and LASD [Los Angeles County Sheriffs Department] approved a settlement in a civil action where Ahmad Burrell, Rory Fontanelle, and Aaron Cunningham were attacked over a three day period, sustaining serious injuries. Although the deputies had known that Hispanic gangs were going to attack African Americans, ... the deputies failed to provide reasonable security and Burrell was attacked in the housing dormitory and the attackers were able to stab him twenty-four (24) times, some causing serious and permanent injury to his abdomen and head.”
In paragraph 41, Starr alleges that on October 21, 2003, “inmate Ki Hong was killed by three inmates who entered the [1199]*1199dayroom where Hong was housed.... Notice of numerous violations showing deputies failing to provide reasonable security and abandoning their duties, their lax discipline and failure to supervise were given to BACA by his in-house lawyers, yet the inmate on inmate violence continued. This was the first of five inmate-on-inmate killings that occurred in the jail system over a six-month period.”
In paragraph 42, Starr alleges that on December 6, 2003, “Inmate Prendergast was beaten periodically over several hours from about 6:00 p.m., to early next morning by ... two of his three cellmates.... Again, notice of numerous violations showing deputy failing to provide reasonable security to the entire cell block, lax discipline and failure to supervise were presented to BACA, yet the inmate on inmate violence continued.”
In paragraph 43, Starr alleges that on December 9, 2003, “inmate Mario Alvarado ... was killed in a holding cell.... Deputies responsible for providing reasonable security failed to ... do so, and the inmates who beat Alvarado had so much time they [were able to] conceal[ ] his dead body under clothes and trash.... Again, notice of numerous violations showing deputy failing to provide reasonable security to the holding cell, lax discipline and failure to supervise were presented to BACA[.]”
In paragraph 44, Starr alleges that on December 13, 2003, a deputy falsified the contents of a statement by a pre-trial detainee, Jose Beas, so that the falsified statement recounted that Beas had admitted to inappropriate touching of a minor. Beas was classified as an inmate who should be kept away from the general prison population, and was “given a wrist band that identified him as such,” but he was placed in a holding tank with “general population inmates.” “Beas was immediately beaten by the other inmates and suffered brain damage. BACA was named as a defendant in that civil case and knew of the allegations of failure to provide reasonable security to the holding cell, lax discipline and failure to supervise!,] and [he] approved the settlement[.]”
In paragraph 45, Starr alleges that on January 12, 2004, “inmate Kristopher Faye was stabbed to death by several inmates with jail-made knives---- Fay[e] was African American and the attackers were Hispanic. Deputies responsible for keeping the cell gates in the housing module close[d] allowed all the cell gates in the module to remain open which increased the danger of violence and was in violation of LASD policy.... Numerous violations showing errors in classification, placing highly dangerous inmates with histories of violence with nonviolent inmates presenting low security risk, deputy failing to provide reasonable security to the holding cell, lax discipline and failure to supervise were again presented to BACA in official reports!.]”
In paragraph 46, Starr alleges that on April 20, 2004, “inmate Raul Tinajero was killed in his cell in the jail, by inmate Santiago Pineda. Pineda had a history of prior misconduct in the jail[.] ... Tinajero was to be a witness in a criminal case against Pineda.... Due to the monitoring failures of the deputies and inadequate procedures with regard to the escorting of inmates, Pineda was able to enter Tinajero’s cell unchallenged by the deputies responsible for providing reasonable security, kill Tinajero undetected, [and] remain in Tinajero’s cell for five hours undetected by deputies. Numerous violations showing errors in classification, deputies failing to provide reasonable security to the housing cells, lax discipline and failure to supervise were again presented to BACA in official reports!.]”
[1200]*1200In paragraph 47, Starr alleges that on May 23 or 24, 2004, inmate Antonio Fernandez was killed by other inmates in the dormitory. “The deputy that was assigned to monitor the dormitory had abandoned her duties and left her post unattended, and the post was vacant for approximately 20 minutes during which time the assault occurred.... [T]he failure to provide reasonable security to [the] housing area, lax discipline and failure to supervise were again presented to BACA[.]”
In paragraph 48, Starr alleges, “BACA received notice from The Special Counsel to the Los Angeles County Sheriffs Department, in the 17th Semiannual Report (February 2004) and the 18th Semiannual Report (August 2004) of increasing levels of inmate violence in the jails.”
In paragraph 49, Starr alleges that in “February 2005 BACA received notice from The Special Counsel to the Los Angeles County Sheriffs Department, in the 19th Semiannual Report that his deputies[’] conduct was ... costing county tax payers millions of dollars annually in payments of civil judgments and settlements, in cases where the internal investigations had found no wrong doing. In all, BACA was notified by his Special Counsel that ... of twenty-nine (29) cases involving police misconduct [that] settled for $100,000 or more over the past five years, only eight resulted in any type of discipline to the involved officers or policy change in the Department.”
In paragraph 50, Starr alleges that on February 3, 2005, Special Counsel Merrick Bobb presented to BACA a finding of inmate abuse, contained in a report to the Los Angeles County Board of Supervisors. The report found “that ‘Los Angeles County’s largest jail is so outdated, understaffed and riddled with security flaws that it jeopardizes the lives of guards and inmates.’ The Special Counsel’s report criticized the County Jail in downtown Los Angeles for ‘failing to prevent dangerous inmates from being housed with lower-risk inmates.... ’ The report concluded that Men[’]s[] Central Jail ‘is nightmarish to manage’ and suffers from ‘lax supervision and a long-standing jail culture that has shortchanged accountability for inmate safety and security.’ ”
In paragraph 52, Starr alleges that on October 24, 2005, Chadwick Shane Cochran was booked into county jail for a nonviolent misdemeanor. Due to mental health difficulties, Cochran was classified to be placed in a mental health facility located within the jail. “Due to errors by staff his protective housing was terminated and he was sent to general population on November 16, 2005, where he was beaten to death a few hours later that day. Deputies compounded the error of removing Cochran from protective status and left a red color identification card which led the attacking inmates to believe that he was a ‘snitch’ or informant. The deputies responsible for the safety of inmates abandoned their post and supervision of the locked day room in which 40 other inmates, some of whom were classified as violent ‘high risk’ accused murderers and gang members, and known violent offenders. Cochran was screaming and many other inmates were yelling for them to stop, but no deputy resumed their responsibility to provide reasonable security until the inmates had grown tired of beating Cochran and hid his body under clothing and food trays. The numerous errors in classification, deputies failing to provide reasonable security to the day room housing cells, lax discipline and failure to supervise were again presented to BACA in official reports!.]”
In paragraphs 13 through 19, Starr alleges that he was attacked three months after Cochran was killed. We recounted [1201]*1201the details of this alleged attack at the beginning of onr opinion.
In paragraph 32, Starr alleges that Sheriff “BACA knew or reasonably] could have known[ ] of his subordinates’ ongoing constitutional violations ..., of the failure to provide reasonable security at the jail, failure to prevent inmate on inmate violence, failure to monitor inmates, lax or no supervision by his subordinate supervisors, use of excessive force on inmates, failure to investigate incidents ... involving inmate on inmate violence, failure to protect, failure to implement indicated policies and procedures regarding, including but not limited to[,] the use of inmates as trustees!.] BACA failed to act to prevent his subordinates!’] ongoing unconstitutional conduct!;] ... he acquiesced, condoned or ratified a custom, practice or policy of ongoing misconduct by his subordinate deputies and supervisors.” In paragraph 35, Starr alleges that “Sheriff BACA ... became aware, or should have become aware, and should have taken corrective actions to prevent repeated incidents” of derelictions of duty by his subordinates.
2. Pleading Standards under Rule 8(a)
We hold that the foregoing allegations are sufficient to satisfy Rule 8(a). The text of Rule 8(a) has not been changed since the initial promulgation of the Federal Rules of Civil Procedure in 1938. In relevant part, it provides:
(a) Claim for Relief. A pleading that states a claim for relief must contain:
(2) a short and plain statement of the claim showing that the pleader is entitled to relief!.]
The theory of Rule 8(a), and of the federal rules in general, is notice pleading. The 1938 federal rules replaced a system in which the federal trial courts had followed the procedural rules of the different states in which they sat. Conformity Act of 1872, Act of June 1, 1872, ch. 225, § 5, 17 Stat. 196, 197 (codified in Rev. Stat. § 914 (1878)). Ever since 1938, the federal civil rules have been applicable in all federal courts. They apply uniformly to all civil cases, whatever the cause of action or subject matter of the suit. See Fed.R.Civ.P. 1 (“These rules govern the procedure in all civil actions and proceedings in the United States district courts, except as stated in Rule 81.”).
The state pleading rules had largely required code, or fact, pleading, under which pleaders were required to allege very specifically the factual bases for their claims. By contrast, under the federal rules a complaint is required only to give the notice of the claim such that the opposing party may defend himself or herself effectively. The theory of the federal rules is that once notice-giving pleadings have been served, the parties are to conduct discovery in order to learn more about the underlying facts. When they have learned the facts, the parties can settle or seek judgment. If the case does not settle but the material facts are clear, the court will grant summary judgment. If material facts are genuinely disputed, the case will go to trial. That, in any event, is the theory.
In practice, the operation of the federal pleading rules is more nuanced. In some cases, particularly complex commercial cases, notice pleading rules give an advantage — perhaps an unfair advantage — to the plaintiff. If a plaintiff can survive a motion to dismiss on the pleadings in such cases, he or she can put the defendant to enormous expense in discovery. In practical terms, this means that the settlement value of a suit jumps substantially the moment the complaint survives a motion to dismiss. In recognition of this practical reality, Congress took some aspects of pleading in federal securities cases out of the federal rules entirely, [1202]*1202imposing by statute something like the old code pleading system as a way of protecting defendants from some of the settlement pressures that exist under the Rule 8(a) regime. Private Securities Litigation Reform Act of 1995 (“PSLRA”), Pub.L. 104-67, 109 Stat. 737, Title I, § 101, codified at 15 U.S.C. § 78u-4(b); see also Tellabs, Inc. v. Makor Issues & Rights, Ltd., 551 U.S. 308, 313, 127 S.Ct. 2499, 168 L.Ed.2d 179 (2007) (“Exacting pleading requirements are among the control measures Congress included in the PSLRA. The PSLRA Act requires plaintiffs to state with particularity both the facts constituting the alleged violation, and the facts evidencing scienter.”); Zucco Partners, LLC v. Digimarc Corp., 552 F.3d 981, 990 (9th Cir.2009) (“All securities fraud complaints since 1995 ... are subject to the more exacting pleading requirements of the PSLRA, which significantly altered pleading requirements in securities fraud cases.” (internal quotation marks omitted)).
In several recent cases, without benefit of statute, the Supreme Court has applied what appears to be a higher pleading standard under Rule 8(a). In Dura Pharmaceuticals, Inc. v. Broudo, 544 U.S. 336, 125 S.Ct. 1627, 161 L.Ed.2d 577 (2005), the Court dealt with allegations of damage causation in a federal securities case; this allegation was not covered by the new higher pleading standard imposed by the PSLRA. The Court “assume[d], at least for argument’s sake, that neither [Rule 8(a)(2) ] nor the securities statutes impose any special further requirement in respect to the pleading of proximate causation or economic loss.” Id. at 346, 125 S.Ct. 1627. After “conced[ing] that ordinary pleading rules are not meant to impose a great burden upon a plaintiff,” the Court wrote,
At the same time, allowing a plaintiff to forgo giving any indication of the economic loss and proximate cause that the plaintiff has in mind would bring about harm of the very sort the statutes seek to avoid. Cf. H.R. Conf. Rep. No. 104-369, p. 31 (1995) [U.S.Code Cong. & Admin .News 1995, pp. 679, 730] (criticizing “abusive” practices including “the routine filing of lawsuits ... with only [a] faint hope that the discovery process might lead to some plausible cause of action.”). It would permit a plaintiff “with a largely groundless claim to simply take up the time of a number of other people, with the right to do so representing an in temrem increment of the settlement value, rather than a reasonably founded hope that the [discovery] process will reveal relevant evidence.” Blue Chip Stamps [v. Manor Drug Stores], 421 U.S. [723, 741 [95 S.Ct. 1917, 44 L.Ed.2d 539] (1975)].
Id. at 347, 125 S.Ct. 1627 (some alterations in original).
In Bell Atlantic Corp. v. Twombly, 550 U.S. 544, 127 S.Ct. 1955, 167 L.Ed.2d 929 (2007), plaintiff alleged a violation of Section 1 of the Sherman Act. Applying the pleading standard of Rule 8(a), the Court wrote “that an allegation of parallel conduct and a bare assertion of conspiracy will not suffice,” id. at 556, 127 S.Ct. 1955, even though the existence of parallel conduct and a conspiracy would violate Section 1. The Court required more than just notice of the claim. It required that the claim be plausible. “[W]e hold that stating such a claim requires a complaint with enough factual matter (taken as true) to suggest that an agreement was made. Asking for plausible grounds to infer an agreement does not impose a probability requirement at the pleading stage; it simply calls for enough fact to raise a reasonable expectation that discovery will reveal evidence of illegal agreement.” Id.
The Court made clear in Twombly that it was concerned that lenient pleading standards facilitated abusive antitrust liti[1203]*1203gation. It provided, with approval, the following citation:
See also Car Carriers, Inc. v. Ford Motor Co., 745 F.2d 1101, 1106 (C.A.7 1984) (“[T]he costs of modern federal antitrust litigation and the increasing caseload of the federal courts counsel against sending the parties into discovery when there is no reasonable likelihood that the plaintiffs can construct a claim from the events related in the complaint”)[.]
Id. at 558, 127 S.Ct. 1955. The Court wrote, further, “Probably, then, it is only by taking care to require allegations that reach the level suggesting conspiracy that we can hope to avoid the potentially enormous expense of discovery in cases with no ‘reasonably founded hope that the [discovery] process will reveal relevant evidence’ to support a § 1 claim. Dura, 544 U.S. at 347, 125 S.Ct. 1627.” Id. at 559-60, 125 S.Ct. 1627 (some internal quotation marks omitted).
Finally, in Iqbal, plaintiff Iqbal, a Muslim American man, brought a Bivens action alleging deliberate discrimination by Attorney General Ashcroft and F.B.I. Director Mueller. Applying Rule 8(a), the Court held that the allegations in Iqbal’s complaint were insufficient. In the Court’s view, the allegations were neither entitled to the presumption of truth nor plausible.
Iqbal’s complaint alleged that defendants “ ‘knew of, condoned, and willfully and maliciously agreed to subject’ [him] to harsh conditions of confinement ‘as a matter of policy, solely on account of [his] religion, race, and/or national origin and for no legitimate penological interest.’ ” Id. at 1944 (second alteration in original). The complaint alleged that “Ashcroft was the ‘principal architect’ of this invidious policy, ... and that Mueller was ‘instrumental’ in adopting and executing it[.]” Id. at 1951. The Court held that these allegations were “bald,” and that their “conclusory nature ... disentitle^] them to the presumption of truth.” Id.
The complaint further alleged that the two defendants had caused the arrest and detention of “thousands of Arab Muslim men ... as part of [the government’s] investigation of the events of September 11.” Id. at 1951. It alleged that the defendants had “purposefully designated] detainees ‘of high interest’ because of their race, religion, or national origin.” Id. The Court held that this allegation of discriminatory purpose was implausible and therefore not a sufficient allegation under Rule 8(a): “[G]iven more likely explanations,[the allegations] do not plausibly establish this purpose.” Id. “[The] complaint does not contain any factual allegation sufficient to plausibly suggest [defendants’] discriminatory state of mind.” Id. at 1952.
In two cases decided during roughly the same period, the Court appears to have applied the original, more lenient version of Rule 8(a). In Swierkiewicz v. Sorema N.A., 534 U.S. 506, 122 S.Ct. 992, 152 L.Ed.2d 1 (2002), the Second Circuit had dismissed plaintiffs employment discrimination ease for failure to plead facts establishing a prima facie case of discrimination. The Supreme Court reversed, writing:
[Petitioner’s complaint easily satisfies the requirements of Rule 8(a) because it gives respondent fair notice of the basis for petitioner’s claims. Petitioner alleged that he had been terminated on account of his national origin in violation of Title VII and on account of his age in violation of the ADEA. His complaint detailed the events leading to his termination, provided relevant dates, and included the ages and nationalities of at least some of the relevant persons involved in his termination. These allegations give respondent fair notice of what [1204]*1204petitioner’s claims are and the grounds upon which they rest....
Respondent argues that allowing lawsuits based on conclusory allegations of discrimination to go forward will burden the courts and encourage disgruntled employees to bring unsubstantiated suits. Whatever the practical merits of this argument, the Federal Rules do not contain a heightened pleading standard for employment discrimination suits.... Rule 8(a) establishes a pleading standard without regard to whether a claim will succeed on the merits. “Indeed it may appear on the face of the pleadings that a recovery is very remote and unlikely but that is not the test.” Scheuer [v. Rhodes], 416 U.S. [232] at 236 [94 S.Ct. 1683, 40 L.Ed.2d 90 (1974)].
Id. at 514-15, 122 S.Ct. 992 (emphasis added) (some citations omitted).
In Erickson v. Pardus, 551 U.S. 89, 127 S.Ct. 2197, 167 L.Ed.2d 1081 (2007) (per curiam), the Tenth Circuit had dismissed an Eighth and Fourteenth Amendment deliberate indifference claim for failure to satisfy Rule 8(a). Plaintiff, an inmate in a Colorado state prison, had “alleged that a liver condition resulting from hepatitis C required a treatment program that officials had commenced but then wrongfully terminated, with life-threatening consequences.” Id. at 89-90, 127 S.Ct. 2197. The Tenth Circuit deemed the allegations of the complaint “conclusory” and dismissed on the pleadings. Id. at 90, 127 S.Ct. 2197. The Court emphatically disagreed: “The holding departs in so stark a manner from the pleading standard mandated by the Federal Rules of Civil Procedure that we grant review.” Id. The Court wrote, “[The complaint] alleged this medication was withheld ‘shortly after’ petitioner had commenced a treatment program that would take one year, that he was ‘still in need of treatment for this disease,’ and that the prison officials were in the meantime refusing to provide treatment. This alone was enough to satisfy Rule 8(a)(2).” Id. at 94, 127 S.Ct. 2197 (citations omitted).
The juxtaposition of Swierkiewicz and Erickson, on the one hand, and Dura, Twombly, and Iqbal, on the other, is perplexing. Even though the Court stated in all five cases that it was applying Rule 8(a), it is hard to avoid the conclusion that, in fact, the Court applied a higher pleading standard in Dura, Twombly and Iqbal. The Court in Dura and Twombly appeared concerned that in some complex commercial cases the usual lenient pleading standard under Rule 8(a) gave too much settlement leverage to plaintiffs. That is, if a non-specific complaint was enough to survive a motion to dismiss, plaintiffs would be able to extract undeservedly high settlements from deep-pocket companies. In Iqbal, by contrast, the Court was concerned that the usual lenient standard under Rule 8(a) would provide too little protection for high-level executive branch officials who allegedly engaged in misconduct in the aftermath of September 11, 2001. To the extent that we perceive a difference in the application of Rule 8(a) in the two groups of cases, it is difficult to know in cases that come before us whether we should apply the more lenient or the more demanding standard.
But whatever the difference between these cases, we can at least state the following two principles common to all of them. First, allegations in a complaint or counterclaim must be sufficiently detailed to give fair notice to the opposing party of the nature of the claim so that the party may effectively defend against it. Second, the allegations must be sufficiently plausible that it is not unfair to require the opposing party to be subjected to the expense of discovery.
[1205]*12053. Evaluation of Starr’s Complaint
Viewed in the light of all of the Supreme Court’s recent cases, we hold that the allegations of Starr’s complaint satisfy the standard of Rule 8(a). We do not so hold merely because Starr’s complaint, like the complaint in Erickson, alleges deliberate indifference in violation of the Eighth and Fourteenth Amendments. Rather, we so hold because his complaint complies with the two principles just stated.
First, Starr’s complaint specifically alleges numerous incidents in which inmates in Los Angeles County jails have been killed or injured because of the culpable actions of the subordinates of Sheriff Baca. The complaint specifically alleges that Sheriff Baca was given notice of all of these incidents. It specifically alleges, in addition, that Sheriff Baca was given notice, in several reports, of systematic problems in the county jails under his supervision that have resulted in these deaths and injuries. Finally, it alleges that Sheriff Baca did not take action to protect inmates under his care despite the dangers, created by the actions of his subordinates, of which he had been made aware. These allegations are neither “bald” nor “conclusory.” Iqbal, 129 S.Ct. at 1951. Rather, they are sufficiently detailed to give notice to Sheriff Baca of the nature of Starr’s claim against him and to give him a fair opportunity to defend against it.
Second, the allegations in Starr’s complaint are plausible. They may or may not ultimately be proven by evidence. But the question is not truth or even probability. Rule 8(a) “does not impose a probability requirement at the pleading stage; it simply calls for enough fact to raise a reasonable expectation that discovery will reveal evidence” to support the allegations. Twombly, 550 U.S. at 556, 127 S.Ct. 1955.
Conclusion
We hold that the Supreme Court’s decision in Iqbal did not alter the substantive requirements for supervisory liability claims in an unconstitutional conditions of confinement case under the Eighth and Fourteenth Amendments where deliberate indifference is the applicable standard. We also hold that Starr has sufficiently alleged a supervisory liability claim of deliberate indifference against Sheriff Baca. We therefore reverse the district court’s dismissal of Starr’s claim against Sheriff Baca and remand for further proceedings.
REVERSED AND REMANDED.