SELYA, Circuit Judge.
This appeal poses an intriguing question of constitutional law. Suppose that the following scenario exists: (1) the police arrest a person pursuant to a facially valid warrant, supported by probable cause; (2) the person, though named in the warrant, asserts that he is actually innocent; and (3) the police come to believe that claim. In those circumstances, can the officers be held liable under 42 U.S.C. § 1983 for their refusal unilaterally to release the person whom they have arrested? The district court answered this question unconditionally in the affirmative. We reverse.
I. BACKGROUND
This case had its genesis in an arrest that occurred in Middleboro, Massachusetts, on September 17, 1994, when a state trooper stopped David Buckley for driving under the influence of alcohol.1 Buckley (who had no driver’s license or other identification on his person) palmed himself off to the arresting officer as William Brady and supplemented this misidentification with Brady’s authentic address, date of birth, and social security number. When the imposter failed to appear in court to respond to the charge, a warrant issued in Brady’s name.
That warrant was still outstanding on Saturday evening, March 4, 1995, when the Rockland police department received word of a brawl. The officer who responded to the scene encountered plaintiff-appellee William Brady and detained him because of the outstanding warrant, unaware that he had nabbed the real William Brady, not the poseur whose default had inspired the issuance of process.
Informed that the warrant had borne fruit, a Massachusetts state trooper, Thomas Majenski, made a beeline for the Rockland station house and assisted in transporting Brady to the state police barracks in Bourne. There, other troopers placed him in a holding cell. From the [107]*107outset, Brady proclaimed his innocence, insisting that he had not been stopped for drunk driving in Middleboro the previous year.
Shortly after Brady’s arrival, his new custodians began looking into his protested innocence. An examination of the original arrest report (Report No. 1), transmitted by facsimile from Middleboro, revealed certain discrepancies when compared with the Rockland arrest report (Report No. 2) (e.g., Report No. 1 indicated that Brady had a tattoo and that his mother’s maiden name was “Kowalski,” whereas Report No. 2 noted no tattoos and listed the detainee’s mother’s maiden name as “Kozloski”). Moreover, the particulars concerning height, weight, hair and eye color did not correlate precisely. Trooper Steven Vrona proceeded to contact the officer who had cited the allegedly inebriated motorist, and this conversation provided further reason to believe that Brady probably was not the person who had been stopped in Middle-boro.
Suspecting that they might have the wrong man (notwithstanding the exact match between the name that appeared on the warrant and the name of the person in custody), the troopers unsuccessfully attempted to glean information from Brady about who might have preempted his identity. They then essayed to arrange his release on bail. At around midnight, a bail commissioner arrived at the barracks in response to the troopers’ importuning and offered to turn Brady loose on personal recognizance upon his (Brady’s) execution of an agreement to appear voluntarily for arraignment. Brady declined, apparently fearing that he might somehow inculpate himself by signing the paper. On Sunday, March 5, the troopers tried to involve an attorney on Brady’s behalf, but their efforts came to naught. The next day, Brady was taken to the first available court session, arraigned, and released. He had spent a day and a half in custody. The charges against him eventually were dismissed.
Brady sued under 42 U.S.C. § 1983, claiming that the troopers had violated his right to be free from unreasonable seizures and wrongful detention. See U.S. Const, amends. IV & XIV, § 1. Although he did not challenge either the validity of the default warrant or the propriety of the initial arrest, he contended that the troopers had a constitutional obligation to release him from custody, despite the command of the facially valid warrant, once it had become apparent to them that they were holding the wrong person.2
The defendants moved for summary judgment, asseverating that their handling of the situation had not violated Brady’s rights, and that, in all events, the doctrine of qualified immunity shielded them from liability for money damages. The district court granted brevis disposition in favor of Colonel Charles Henderson (the state police superintendent) and Majenski (whose only involvement had been in ferrying Brady from Rockland to Bourne), but it denied similar relief to the four troopers who served as Brady’s principal custodians at the Bourne barracks (Vrona, Sergeant Maryann Dill, and Troopers Kenneth J. Hudson, Jr., and Douglas Mendes). See Brady v. Dill, 24 F.Supp.2d 129 (D.Mass.1998). The quartet of disappointed troopers then prosecuted this interlocutory appeal. See Camilo-Robles v. Zapata, 175 F.3d 41, 45 (1st Cir.1999) (explaining the basis on which public officials may bring interlocutory appeals from pretrial orders rejecting assertions of qualified immunity).
II. DISCUSSION
When qualified immunity is at issue, an inquiring court first must ask whether the Constitution recognizes the right asserted by the plaintiff. See Conn v. Gabbert, - U.S. -, -, 119 S.Ct. [108]*1081292, 1295, 143 L.Ed.2d 399 (1999). In this instance, Brady argues that the Fourth Amendment’s prohibition against unreasonable seizures obligates officers who have made a “matched” arrest pursuant to a facially valid warrant (i.e., an arrest in which the suspect’s identity matches the stated identity of the person denominated in the warrant) to release the person unilaterally if and when they come to believe that he is innocent. We think that this claim, as it relates to the facts of this case, is foreclosed by Baker v. McCollan, 443 U.S. 137, 99 S.Ct. 2689, 61 L.Ed.2d 433 (1979).
Like this case, Baker involved the “matched” arrest, over vigorous protest, of a victim of mistaken identities pursuant to what was, on its face, a valid warrant. The sheriffs office detained McCollan for several days, releasing him only after comparing his visage to a photograph of the wanted man (McCollan’s brother, who, as matters turned out, had used McCollan’s identification when originally apprehended). See id. at 140-41, 99 S.Ct. 2689. McCollan subsequently sued the sheriff under section 1983, seeking damages for the deprivation of his liberty. See id. at 141, 99 S.Ct. 2689. The district court directed a verdict in the sheriffs favor, but the court of appeals reversed and remanded for a new trial. See McCollan v. Tate, 575 F.2d 509, 511 (5th Cir.1978). The Supreme Court then granted the sheriffs certiorari petition. See Baker v. McCollan, 439 U.S. 1114, 99 S.Ct. 1015, 59 L.Ed.2d 71 (1979).
Although McCollan had framed his suit in terms of the Fourteenth Amendment, the Court began by considering whether the arrest itself had violated the Fourth Amendment. See Baker, 443 U.S. at 142-43, 99 S.Ct. 2689 (noting that the Fourth Amendment has been incorporated into the Fourteenth). The Court concluded that because the warrant naming McCollan was valid on its face, probable cause existed for the arrest and, hence, the Fourth Amendment was not implicated. See id. at 143-44, 99 S.Ct. 2689; see also Graham v. Connor, 490 U.S. 386, 396, 109 S.Ct. 1865, 104 L.Ed.2d 443 (1989) (observing that, even if the wrong person is arrested, there is no Fourth Amendment violation as long as the arrest is based on probable cause) (citing cases).
Once the Fourth Amendment had dropped out of the equation, the Court considered whether McCollan had been deprived of any of the specific subset of procedural guarantees, incorporated into the Fourteenth Amendment’s Due Process Clause, that come into play after completion of an arrest (e.g., the prohibition against excessive bail, the guarantee of a speedy trial, and the like). See Baker, 443 U.S. at 144-46 & n. 3, 99 S.Ct. 2689. Because McCollan had not been deprived of any such rights, the Court concluded that the complainant had failed to prove a constitutional wrong. See id. at 145-47, 99 S.Ct. 2689. While conceding that a lengthy detainment in the face of repeated claims of innocence might in extreme circumstances furnish the basis for a constitutional violation, the Court was “quite certain that a detention of three days over a New Year’s weekend does not and could not amount to such a deprivation.” Id. at 145, 99 S.Ct. 2689. In the bargain, the Court also rejected, at least implicitly, any claim that the detainment constituted a substantive due process violation. See id. at 147-49, 99 S.Ct. 2689 (Blackmun, J., concurring).
Baker is compelling here. Given that Brady does not challenge the validity of the arrest itself — he was, after all, the very person named in the outstanding warrant — the Fourth Amendment (which governs the legitimacy of the arrest and its incidents) is not at issue. See id. at 143-44, 99 S.Ct. 2689. The question, then, is whether Brady’s post-arrest procedural guarantees were abridged. To prevail on such a battleground, Brady must do more than show that the troopers made a mistake. See id. at 145, 99 S.Ct. 2689 (treating the fact that McCollan was innocent of [109]*109the charges underlying the warrant as “largely irrelevant to his claim of deprivation of liberty without due process of law”).
In all events, the answer to the question is in the negative. The record shows beyond peradveriture of doubt that the appellants afforded Brady more than the full panoply of post-arrest rights that the Constitution demands: despite the fact that he was the person designated in the default warrant, the troopers went to great pains to gather information bearing on .his situation, tried ‘to assist in securing his prompt release, and arraigned him before an impartial magistrate at the earliest opportunity. Under these circumstances, there is no foundation for a claim that Brady’s post-arrest rights were abridged.
Viewed through the Baker prism, this conclusion effectively ends the matter. Because, under parallel circumstances, the Supreme Court pronounced a three-day detention as failing to constitute a .deprivation of liberty without due process, it would take circumstances much more egregious than Brady’s for us to conclude that a weekend detention of approximately thirty-six hours, accompanied by a concerted effort on the part of the police to secure the detainee’s release, resulted in a wrong of constitutional dimensions. Accord Sanchez v. Swyden, 139 F.3d 464, 468-69 (5th Cir.1998) (rejecting section 1983 claim premised on similar factual circumstances on the authority of Baker).
In an effort to escape Bakers deadly embrace, Brady urges us to read the Court’s words narrowly. In his view, Baker stands only for the rule that when a person in custody protests his innocence, police officers have no affirmative obligation to investigate. Baker, Brady maintains, does not address situations in which police officers, after an arrest, do investigate and come to possess “actual knowledge” that the detained person, though named in an outstanding warrant, is a victim of mistaken identities. In such an eventuality, Brady posits, the Constitution requires the officers to release the detainee without further ado. The district court endorsed this cramped reading of Baker and refused to grant the appellants’ motion for summary disposition because it perceived a factual dispute as to whether they had actual knowledge of Brady’s innocence.3 See Brady, 24 F.Supp.2d at 134-35.
To support this ruling, Brady cites to Gay v. Wall, 761 F.2d 175 (4th Cir.1985). There, a warrant had issued for Gay’s arrest after two eyewitnesses had identified him as the perpetrator of a crime. See id. at 176. Acting upon the warrant, the police arrested Gay, kept him in custody for several weeks, and released him only after they had arrested someone else. See id. Gay sued under section 1983, alleging that, as early as the day of the arrest, the police officers were certain that he was innocent and had so stated, yet nonetheless kept him in custody for several weeks. See id. Thus, Gay asserted, the officers had “knowingly, unlawfully, violently, and without probable cause” arrested him, depriving him of an array of constitutional rights. See id. (internal quotation marks omitted).
Although the district court had granted summary judgment in favor of the defendants on the authority of Baker, a panel of the Fourth Circuit reversed, maintaining that Baker does “not involve actual knowledge of the defendant’s innocence, but rather the failure to take affirmative steps to determine his innocence.” Id. at 178-79, 99 S.Ct. 2689. Thus, the panel concluded, if the plaintiffs factual allegations could be proven, “the defendants’ conduct may well be actionable under § 1983.” Id. at 179, 99 S.Ct. 2689.
We do not believe that Brady’s reliance on Gay removes his case from Bakers compass. Brady’s minor premise is unarguably correct: the Baker Court de-[110]*110dined to impose upon police officers an affirmative duty of investigating every claim of innocence raised during a relatively short period of detention. See Baker, 443 U.S. at 145-46, 99 S.Ct. 2689. But his major premise — -that the police must unilaterally release a person detained pursuant to a facially valid warrant directing his arrest if they conclude that he is innocent — -is too much of a stretch.
Gay is distinguishable, for the detention there lasted much longer and the arrest itself was on shaky ground. Equally as important, the Fourth Circuit has backed away from Gay. In Brooks v. City of Winston-Salem, 85 F.3d 178 (4th Cir.1996), the court, characterizing Gay as a case that stands for the proposition “that a defendant is deprived of substantive due process by continued prosecution in the absence of probable cause,” stated that Gay’s foundation had been irretrievably compromised by more recent Supreme Court decisions.4 See Brooks, 85 F.3d at 184 n. 6 (citing, inter alia, Albright v. Oliver, 510 U.S. 266, 114 S.Ct. 807, 127 L.Ed.2d 114 (1994)).
To be sure, Brady does not cast his argument in terms of substantive due process; instead, he endeavors to use Gay as a wedge to extend the Fourth Amendment’s protections to the post-arrest context. We doubt that Gay, fairly read, supports this gloss (although it is difficult to tell, for Gay leaves us guessing as to what act by the police officers the panel thought was wrongful and which specific constitutional provision the panel suspected the officers might have violated). If, however, Gay is to be construed in this free-wheeling manner, we must reject it as antithetical both to the teachings of Baker and to this court’s pronouncements in Thompson v. Olson, 798 F.2d 552 (1st Cir. 1986).
We begin with Baker. Brady’s position clashes head-on with the Baker Court’s conclusion that once a “matched” arrest pursuant to a facially valid warrant supported by probable cause has been completed, a detainee’s protections from unlawful custody no longer repose in the Fourth Amendment.5 See Baker, 443 U.S. at 143-44, 99 S.Ct. 2689; see also Brothers v. Klevenhagen, 28 F.3d 452, 455-56 (5th Cir.1994) (explaining that once an arrest is complete, a criminal defendant’s protection no longer emanates from the Fourth Amendment, but from other rights recognized by the Due Process Clause); Villanova v. Abrams, 972 F.2d 792, 797 (7th Cir.1992) (similar); cf. Brooks, 85 F.3d at 184 (concluding that the Fourth Amendment does not require a police officer to attempt to halt criminal proceedings when he concludes that the criminal defendant is innocent). As Baker teaches, “[t]he Constitution does not guarantee that only the guilty will be arrested.” 443 U.S. at 145, 99 S.Ct. 2689.
[111]*111This disclaimer is not as' harsh as it might seem. Persons who are arrested enjoy “manifold procedural- protections,” quite apart from those embodied in the Fourth Amendment, that allow them to establish their innocence. Id. Our legal system effectuates these procedural protections- — -in a manner that adds further safeguards for the innocent — by placing the “ultimate determination of [the arres-tee’s] claims of innocence ... in the hands of the judge and the jury.” Id. at 146, 99 S.Ct. 2689. Baker thus venerates the separation of functions among various government actors. See id. at 145, 99 S.Ct. 2689 (endorsing a “reasonable division of functions between law enforcement officers, committing magistrates, and judicial officers” as “entirely consistent with ‘due process of law5 ”). This respect for the separation of functions, the significance of which the Court has noted in related contexts, see, e.g., Gerstein v. Pugh, 420 U.S. 103, 117-18, 95 S.Ct. 854, 43 L.Ed.2d 54 (1975), largely explains why the Baker Court declined to impose on police officers an affirmative duty of investigating claims of innocence.6 The same principle also bears on why the Court deemed adherence to the archetypical post-arrest due process guarantees sufficient to protect McCollan’s rights (and, ultimately, to defeat his section 1983 claim).
We hewed to this very line in Thompson which, as a precedent of this court, further binds us in our consideration of the case at hand. See Williams v. Ashland Eng’g Co., 45 F.3d 588, 592 (1st Cir.1995) (outlining the parameters of the law of the circuit doctrine). Thompson involved a warrant-less arrest in which the police officer himself had made the initial probable cause determination. The plaintiff then filed a section 1983 suit founded on a theory of substantive due process, coupled with a pendent state-law false imprisonment claim. In discussing the latter, we noted the general rule, which we considered applicable to cases of warrantless arrests, that “once the arrest has been properly effected, it is the magistrate and not the policeman who should decide whether probable cause has dissipated to such an extent following arrest that the suspect should be released.” Id. at 556; accord Romero v. Fay, 45 F.3d 1472, 1481 (10th Cir.1994) (rejecting a section 1983 claim based on the police’s refusal.to release an individual who maintained his innocence after a warrantless arrest in light of Baker’s “recognition that the judicial system represents the proper forum in which to determine the innocence of an arrestee”). If the rule we recognized in Thompson applies to a warrantless arrest, it must apply, a fortiori, to an arrest of a person named in a facially valid warrant.7
Important considerations undergird the separation of functions recognized in Baker and Thompson, and those considerations are at their zenith when a person who is named in a facially valid warrant, supported by probable cause, is arrested pursuant to that -warrant. When such a [112]*112person asserts that he is a victim of mistaken identities, he in effect is pressing a claim of innocence in fact — a claim not analytically distinct from any other factual defense (say, an alibi defense or a defense premised on a lack of specific intent) tendered by a person whom the police arrest in pursuance of a warrant issued by a judge or magistrate. Regardless of the merits of the defense, our legal system simply does not rely on police officers to determine its bona fides, even though they may have information bearing on that ultimate question and even though they may harbor strong and informed opinions one way or the other. To the contrary, once probable cause has been established, a warrant issued, and an arrest perfected, the ordinary course is for the prosecutor to decide whether to go forward, and if he elects to proceed, for the judicial branch to make the final ascertainment of guilt or innocence' — -not for the police to take matters into their own hands.
One reason for this allocation of deci-sionmaking responsibility is that the prosecutor, the judge, and the jury are institutionally better equipped to make such determinations. The prosecutor, as the official responsible for proving guilt, has the capacity — and the armamentarium — to assemble and assess all the existing evidence and to evaluate whether there is proof enough to press charges. The judge, as a neutral and detached factfin-der, benefits from the formal mechanisms of introduction and consideration of proof (not the least of which is cross-examination) that give his ultimate determination the degree of reliability that our system of justice deems essential to ensure fairness. The jury, similarly, is positioned to make informed judgments as to guilt or innocence upon receipt of tested proof and legal instructions.
The police officer assumes a different posture. Though a trained investigator, he often receives information over time in bits and pieces, and does not have available the same means for marshaling the evidence or the same tools for assessing conflicting evidence ex post. Consequently, in a situation in which a warrant has issued upon probable cause, a police officer is not called upon either to exercise discretion or to weigh the proof. Rather, his obligation is more straightforward: to execute the warrant — which is, after all, a judicially-approved order — according to its tenor and terms, detaining the individual named therein. To place on police officers the additional burden of determining, after a legitimate arrest pursuant to a facially valid warrant, whether the person detained is or is not the guilty party would blur the usual separation of functions. The Constitution imposes no such burden on the police. Cf. Thompson, 798 F.2d at 556 (stating that “having once determined that there is probable cause to arrest, an officer should not be required to reassess [this] probable cause conclusion at every turn, whether faced with the discovery of some new evidence or a suspect’s self-exonerating explanation from the back of a squad car”).
It is, moreover, impossible to subscribe to the wistful supposition (shared by Brady, the district court, and our concurring brother) that police officers who must make conclusions from conflicting evidence gathered during a post-arrest investigation may come to “know” that an arrestee is innocent.8 See Brady, 24 F.Supp.2d at [113]*113134. Absent personal knowledge of Brady’s innocence — and Brady does not aver that any of the appellants were percipient witnesses to the drunk driving or its immediate aftermath — the worst one can say about the troopers who continued to hold Brady in custody is that they came to believe, with some degree of subjective certainty, that the man they had arrested, though named in the warrant, was innocent of the underlying charge. This is not knowledge, but subjective belief — even when embellished by declarative prepositional phrases. See post at 117 (suggesting that police officers may “learn to a certainty” of a detainee’s innocence); id. at 120 (suggesting that officers may “know to a certainty” that they are holding the wrong man). Regardless of rhetoric, this kind of subjective belief, without more, is generally insufficient to justify a police officer’s unilateral release of a person who has been lawfully arrested pursuant to a valid judicial order. Cf., e.g., Whren v. United States, 517 U.S. 806, 811-13, 116 S.Ct. 1769, 135 L.Ed.2d 89 (1996) (explaining that police officers’ subjective intentions are irrelevant to Fourth Amendment probable cause analyses); Graham, 490 U.S. at 397, 109 S.Ct. 1865 (reiterating that subjective intent plays no role in assessing the reasonableness of police officers’ conduct under the Fourth Amendment).
To illustrate the point, it is readily apparent that Brady’s claim that the troopers had “actual knowledge” of his innocence rests on the assumption that the discrepancies between the two arrest reports, coupled with Vrona’s call to the trooper who had stopped the ostensibly inebriated driver in Middleboro, were sufficient to demonstrate conclusively that he was a victim of mistaken identities. What seems like a strong argument with the benefit of hindsight is much more dubious when matters are viewed ex ante. The discrepancies involved things like Brady’s mother’s maiden name (“Kozloski” as opposed to “Kowalski”), the evanescent tattoo, and certain divergent physical traits. But we live in an age where altering physical features may be accomplished with facility, see Blackwell v. Barton, 34 F.3d 298, 304 (5th Cir.1994), where clerical errors in recording, receiving, or transmitting data are commonplace, see United States v. De Leon-Reyna, 930 F.2d 396, 398-99 (5th Cir.1991) (en banc) (per curiam), and where descriptive inaccuracies can occur easily. Thus, courts have concluded with some regularity that relatively minor discrepancies in physical features or other data do not render unreasonable an arrest pursuant to a facially valid warrant. See White v. Olig, 56 F.3d 817, 820 (7th Cir.1995); Rodriguez v. United States, 54 F.3d 41, 46-47 (1st Cir.1995); Blackwell, 34 F.3d at 304; Thompson v. Prince William County, 753 F.2d 363, 364-65 (4th Cir.1985); Johnson v. Miller, 680 F.2d 39, 41 (7th Cir.1982).
The logic underlying these pre-arrest cases applies even more forcefully to discrepancies that come to light only after an arrest has been accomplished. The analogy therefore buttresses this court’s earlier intuition that the initial determination of probable cause should not be undone by a police officer’s assessment of post-arrest evidence that bears adversely on that initial finding. See Thompson, 798 F.2d at 553, 556. Were the law otherwise, there is a considerable risk that a police officer, subjectively convinced that he has the wrong person, might turn loose a wanted criminal.
To complete the picture, we note that Brady’s position presents significant practical problems. To state the obvious, a warrant is a judicial order authorizing an arrest, and, as long as the police are acting in compliance with that order, it is sur-[114]*114passingly difficult to fathom why the proper method of challenging the ensuing detainment should be something other than a prompt hearing before a magistrate. Additionally, the implications of holding the police responsible for not releasing an individual held under a facially valid warrant that bears his name as evidence accumulates pointing to others poses such complexities that it is not constitutionally unreasonable to leave such decisions to the magistrate. Among other things, a contrary rule would create an incentive for police officers not to investigate claims of innocence at all, for fear of incurring liability should they uncover information that would cast doubt upon the putative offender’s guilt.
Perhaps more insidious, Brady’s position has the potential of turning police stations into tribunals for making preliminary determinations of guilt or innocence — an eventuality that Baker explicitly disavows. See Baker, 443 U.S. at 145-46, 99 S.Ct. 2689 (refusing to recognize a constitutional duty on the police’s part to investigate a detainee’s innocence). And, once police feel pressured to make such decisions, they may encroach upon the judiciary’s functions, denigrating the authority of warrants issued under the auspices of judicial officers. Should that come to pass, the concerns about unbridled police action that the Gerstein Court underscored, 420 U.S. at 117-18, 95 S.Ct. 854, may be realized. Such a happenstance would pose a much greater danger to an ordered conception of liberty than the occasional snafu that the separation of functions regime thus far has produced.9
All this is not to say that a police officer may treat evidence of innocence with impunity. He may not. See Thompson, 798 F.2d at 556 (noting that an officer may not, after the initial finding of probable cause, “close his eyes to all subsequent developments”). One standard police function is to provide information to the prosecutor and the courts. Thus, a police officer sometimes may be liable if he fails to apprise the prosecutor or a judicial officer of known exculpatory information. See Hart v. O'Brien, 127 F.3d 424, 446-47 (5th Cir.1997), cert. denied, - U.S. -, 119 S.Ct. 868, 142 L.Ed.2d 770 (1999); Sanders v. English, 950 F.2d 1152, 1162 (5th Cir.1992); Jones v. City of Chicago, 856 F.2d 985, 992-94 (7th Cir.1988); but see Taylor v. Waters, 81 F.3d 429, 435-37 (4th Cir.1996). In these cases, the constitutional wrong results from the officer’s failure to deliver material information to competent authorities. In that respect, the cited cases are unlike the case at bar: when a police officer acts as an information provider, he may be obliged to reveal exculpatory facts (bearing either on innocence or on probable cause) to a prosecutor or a judicial officer, cf. United States v. Agurs, 427 U.S. 97, 111-13, 96 S.Ct. 2392, 49 L.Ed.2d 342 (1976) (concluding that prosecutor has a duty to reveal material exculpatory evidence even in the absence of a specific request), but the Constitution imposes no parallel duty on a police officer to function as a decisionmaker in order to determine the dissipation vel non of probable cause or the actual innocence of a [115]*115person in custody. In such post-arrest cases, it is ordinarily sufficient for the police officer to bring the relevant information to the attention of the prosecutor or the proper judicial official in a timeous fashion.
We say “ordinarily” because we do not mean to suggest that under no circumstances can such a duty arise.10 Thus, despite the Court’s recent efforts at containment of substantive due process initiatives, see, e.g., Collins v. City of Harker Heights, 503 U.S. 115, 125, 112 S.Ct. 1061, 117 L.Ed.2d 261 (1992), we understand Baker to leave open the possibility that, under extreme circumstances, a plaintiff may be able to press such a claim. Then-Justice Rehnquist, writing for the Court in Baker, took pains to note that the Court was not speaking in absolute terms, as if writing a rule of plane geometry. See Baker, 443 U.S. at 144-45, 99 S.Ct. 2689. Depending upon factors such as the length of the detention, the behavior of the police, the source and quality of the information available to them, and the nature of the pretrial procedures afforded by local law, there may be circumstances so egregious as to ground a substantive due process claim. See, e.g., Gray v. Cuyahoga County Sheriffs Dep’t, 150 F.3d 579, 582-84 (6th Cir.1998) (concluding that plaintiff had stated a substantive due process claim when the police had detained him for 41 days despite their possession of a photograph of the wanted person “that bore virtually no resemblance” to him and the ready availability of a physical description of the wanted person which “detail[ed] certain permanent scars” that the plaintiff did not have), cert. denied, - U.S. -, 119 S.Ct. 1763, 143 L.Ed.2d 794 (1999); Rodriguez v. Roth, 516 F.Supp. 410, 412 (E.D.Pa.1981) (reaching similar conclusion where detention had lasted for 30 days). But Brady’s experience, while distasteful, does not sink to such depths.
To summarize, Brady — who was targeted in a facially valid warrant issued by a judicial officer upon probable cause — has no Fourth Amendment claim in respect to a detention that followed a lawful arrest pursuant to that warrant.11 At least in the case of the “matched” warrant here at issue, the officers’ subjective belief as to Brady’s innocence does not justify an “actual knowledge” exception to the general schema that Baker prescribes. Finally, viewed as a matter of due process, Brady’s circumstances do not go beyond the boundaries of McCollan’s (the plaintiff in Baker). Accordingly, the district court should have granted the appellants’ motion for summary judgment.
We add a coda. Even had we concluded that the record might support a finding that the troopers infringed on Brady’s constitutional rights, we nonetheless would uphold their request for summary judgment based on the doctrine of qualified immunity. We explain briefly.
To determine a defendant’s eligibility for qualified immunity, courts must define the right asserted by the plaintiff at an appropriate level of generality and ask whether,' so characterized, that right was clearly established when the harm-inducing conduct .allegedly took place. See [116]*116Anderson v. Creighton, 483 U.S. 635, 639, 107 S.Ct. 3034, 97 L.Ed.2d 523 (1987). This does not mean that a right is clearly established only if there is precedent of considerable factual similarity. See id. at 640, 107 S.Ct. 3034 (explaining that a general rule of constitutional law identified by precedent may clearly apply to the specific conduct at issue, even though “the very action in question has [not] previously been held unlawful”). It does mean, however, that the law must have defined the right in a quite specific manner, and that the announcement of the rule establishing the right must have been unambiguous and widespread, such that the unlawfulness of particular conduct will be apparent ex ante to reasonable public officials. See Wilson v. Layne, - U.S. -, 119 S.Ct. 1692, 1699-1701, 143 L.Ed.2d 818 (1999); Ringuette v. City of Fall River, 146 F.3d 1, 4 (1st Cir.1998); Nereida-Gonzalez v. Tirado-Delgado, 990 F.2d 701, 704 (1st Cir.1993). After all, qualified immunity for public officials serves important societal purposes, and it is therefore meant to protect “all but the plainly incompetent or those who knowingly violate the law.” Malley v. Briggs, 475 U.S. 335, 341, 106 S.Ct. 1092, 89 L.Ed.2d 271 (1986).
Here, the troopers scrupulously executed a judicial order — the arrest warrant that bore Brady’s name — according to its terms. Their reliance on that warrant appears to have been objectively reasonable. Cf. id. at 345, 106 S.Ct. 1092. Insofar as their failure to release Brady unilaterally once they began to believe that he was innocent, that conduct, under the case law discussed supra, likewise appears to be objectively reasonable. Gay is the only case that seems to support Brady’s assertion of a post-arrest constitutional right to be released unilaterally by police officers who come to believe that a person duly apprehended is, in fact, innocent. That case is in obvious tension with Baker and Thompson, and its precedential value is highly suspect in the circuit of its origin. It is, therefore, too slender a reed to ward off a finding of qualified immunity.
The Supreme Court recently held that an asserted right was not clearly established where the plaintiffs were unable to cite “any cases of controlling authority in their jurisdiction at the time of the incident which clearly established the rule on which they [sought] to rely,” and equally failed to “identify] a consensus of cases of persuasive authority such that a reasonable officer could not have believed that his actions were lawful.” Wilson, — U.S. at -, 119 S.Ct. at 1700. The Wilson Court’s reasoning is perfectly tailored to the circumstances here. Thompson, which represents the governing law of this circuit, plainly did not render the troopers’ actions unlawful, and the tenuous status of Gay falls far short of the “persuasive authority” that Wilson envisions.12
[117]*117III. CONCLUSION
The Constitution does not guarantee that the police will never blunder when making arrests, but it establishes certain procedures to ensure that most mistakes will be detected and rectified. Those mechanisms worked in this case. Brady was taken before a judge at the earliest opportunity, promptly released, and thereafter acquitted of any wrongdoing. While we are mindful of the indignities that accompany arrest and subsequent detainment, we are also mindful of the dangers inherent in tipping the delicate constitutional balance that separates the functions assigned to different departments of government. Far from eliminating errors, imposing liability on police officers for honest mistakes of this kind — especially in cases where, from all indications, the officers acted with reasonable dispatch to compensate for any bevue — not only would have a detrimental impact on effective law em forcement, but also would threaten the separation of functions that our constitutional system has deployed as a means of minimizing the occurrence (and mitigating the adverse effects) of those very 'errors.
We need go no further.13 There is no persuasive authority to support Brady’s contention that he was deprived of liberty without due process of law as a result of his regrettable thirty-six hour detention. The appellants are therefore entitled to summary judgment.
Reversed.