Talmadge, J.
— Three individuals subject to detention under chapter 71.05 RCW, the involuntary civil commitment act (the Act), challenge the propriety of their 14-day [901]*901involuntary confinements. Each claims the social worker who testified to the bases for their confinement lacked the qualifications to testify about their alleged mental disorders. Sheldon and Lucas also claim the trial court should have dismissed their petitions because the statutorily required signatories had not signed them.
We hold, under the unique circumstances of the Sheldon and Lucas petitions, the statutory signature requirements for the 14-day confinement petition were met because a physician, as promised in the petition, provided an affidavit in support of each petition before the confinement hearing in lieu of her signature on the petition. We farther hold a social worker is not disqualified as a matter of law from rendering an opinion as to the presence of a mental disorder in a person subject to a 14-day confinement, provided the social worker otherwise qualifies as an expert and the opinion meets the requirements of ER 702 and 703. We affirm the decision of the Court of Appeals sustaining all three 14-day confinements.
ISSUES
1. Should the trial court have dismissed the Lucas and Sheldon petitions because of the lack of a physician’s signature?
2. Was a social worker’s opinion as to whether the three individuals suffered from a mental disorder admissible?
FACTS
A. INVOLUNTARY CONFINEMENT OF ARNOLD SHELDON (A.S.)
On March 11, 1997, the San Juan County Designated Mental Health Professional (CDMHP),1 Robert LeBeau, [902]*902sought emergency detention for Arnold Sheldon. The CD-MHP’s Notice of Emergency Detention stated:
Mr. Sheldon is an 86 year old Caucasian male who was evaluated for involuntary mental health treatment at the request of Charles Silverman, the San Juan County Prosecuting Attorney. Mr. Sheldon has been arrested 14 times in the last 4 months for a variety of charges. These charges were filed after he sent numerous sexually suggestive notes to a next door neighbor and has gone repeatedly to a local paper, The Journal of the San Juans, telling the staff that he now owned the paper and that they needed to leave. Mr. Silverman also reports that Joan Sheldon, the respondent’s wife, has stated to him that Mr. Sheldon has been violent toward her and has threatened to kill her. [Sentence deleted in original]. I did, however, consult with Elizabeth Forsman, who has received numerous letters from Mr. Sheldon, and Dr. Jack Crawford, who had evaluated Mr. Sheldon’s competence to stand trial. I also interviewed Mr. Sheldon.
•Mr. Sheldon presented as disheveled and somewhat dirty He appeared to have feces on his pants. He was generally cooperative with the interview and was oriented to person, place and time. He denied threatening his wife but he did state that she had lied about him in court in order to become his guardian. He did not deny that he had written sexually suggestive notes to Ms. Forsman and stated that he had been sending them to another neighbor as well. He reported that he had done this because “those women are loaded with estrogen—it makes them do crazy things.” He acknowledged that he had been court ordered to stop writing those letters but that he had not because 1) the women involved had not asked him directly to stop; and 2) “because they’re making such fools of themselves.” In consulting with Ms. Forsman, she reports that she is very afraid of Mr. Sheldon, that his notes contain threats to rape her, and that she has had the locks changed in her house out of fear of being harmed by Mr. Sheldon.
During the interview Mr. Sheldon repeated that he owned the Journal of the San Juans, having purchased the paper for $1.00 last December. He felt that the charges against him for harassment, telephone harassment and criminal trespassing were unwarranted as he owns the paper.
[903]*903Mrs. Joan Sheldon was also contacted as a part of this evaluation. . . . She reports that Mr. Sheldon has become increasingly erratic in his thinking and his behavior. He has told friends in town that he is going to kill her. She also reports that he frequently leaves burners on with their stove and that she is concerned he will burn himself and/or their home.
Dr. Crawford reports that Mr. Sheldon is delusional, a danger to himself and is not competent to stand trial.
Based on these facts, Mr. Sheldon was detained as a danger to self, others, and gravely disabled.
Clerk’s Papers (Sheldon) at 1-2. LeBeau filed the Notice of Emergency Detention pursuant to RCW 71.05.150(l)(a), which authorizes a CDMHP to file a petition for initial detention when a person with a mental disorder presents a likelihood of serious harm or is gravely disabled.
Sheldon was briefly hospitalized for a nonpsychiatric medical condition pursuant to RCW 71.05.210, and three days later, on Friday, March 14, 1997, a mental health professional for Skagit County filed a petition for 14 additional days of confinement for Sheldon pursuant to RCW 71.05.230, alleging much the same conduct as the Notice of Emergency Detention. The petition was signed only by Bruce Work, MSW, as the petitioner. In the space designated for the signature of a physician, Work wrote, “In expectation of psychiatrist’s affidavit.” Clerk’s Papers at 6-8. In the petition, Work alleged the following:
Respondent was detained following a series of incidents and arrests over a several month period that indicated a potential danger to others and a loss of cognitive and volitional control. His wife states that she has moved out due to his threatening behavior, but he is not able to care for himself (leaves burners on, def[e]cates in strange places, unable to manage money). When interviewed, Respondent acknowledges his bizarre and antisocial behavior, but insists it is appropriate and normal. Respondent suffers from a mental disorder that causes him to be gravely disabled. No less restrictive options.
Clerk’s Papers at 6-7.
[904]*904On Monday, March 17, 1997, at the beginning of the 14-day confinement hearing before Skagit County Court Commissioner Dave Needy, acting as a judge pro tempore of the Skagit County Superior Court, the State introduced the affidavit of Dr. Kathryn Neracs, a psychiatrist on the staff of the treatment facility in which Sheldon was confined.2 Dr. Neracs’ evaluation averred:
I am a psychiatrist at North Sound E&T [Evaluation & Treatment], and have evaluated Mr. Arnold Sheldon today, 3-14-97. He was admitted to NSd E&T on 3-12-97. He was detained as GD, DTO, DTS. He was detained following a series of incidents and arrests over a several month period, with bizarre and threatening behavior. The first day at NSD Mr. Sheldon developed a high fever, and was transferred to Skagit Valley Hosp., where he was treated for urosepsis (infection of the urine and blood). He was transferred back to NSD today. Mr. Sheldon appears to have mild dementia, and significant delusions. He believes he has inner vision that is never wrong. He denies health problems, although this is clearly not true. I believe he needs further hospitalization to clarify his psychiatric diagnosis, and stabilize him physically and psychologically. He has not yet been treated with any psychiatric medications because of his poor physical health.
Clerk’s Papers at 9. The State provided Sheldon’s counsel a copy of Dr. Neracs’ affidavit just before the hearing.
During the hearing, Sheldon’s wife and Work testified for the State in support of the petition for 14-day involuntary treatment. Work, a CDMHP in Grays Harbor County and Thurston County, gave as his qualifications a master’s degree in social work with a psychiatric specialty. In answer to the question of what information he had reviewed in his evaluation of Sheldon, Work answered he had reviewed Sheldon’s chart and had spoken with Dr. Gaither, Mrs. Sheldon, and Robert LeBeau. Sheldon objected when the State asked Work for his opinion of whether Sheldon suf[905]*905fered from a mental disorder. Sheldon never stated the basis for the objection, but the State has treated the objection as one going to Work’s qualifications to give an opinion on the subject of mental disorder. The trial court denied the objection.
Sheldon made the following statement after all other witnesses had testified.
I am Arnold Sheldon, U.S. citizen, blind,
Report of Proceedings (Sheldon) at 27. At the end of the hearing, the trial court ordered Sheldon detained for 14 further days of involuntary treatment.
B. INVOLUNTARY COMMITMENT OF CHRISTOPHER McClenahan
On March 20, 1997, Christopher McClenahan, a 23-year-old resident of Lynnwood, Snohomish County, was taken into detention pursuant to a Notice of Emergency Detention. McClenahan had returned to his mother’s Lynnwood house after extensive travel, appearing disheveled, having lost all of his clothing during his journeys. At his mother’s home, McClenahan engaged in imaginary conversations and advised his mother that people were out to get him, monitoring him via satellites and radio-waves. McClenahan’s mother finally locked him out of her house until he agreed to take his medications. In response, McClenahan stood outside in the rain for hours and finally climbed onto [906]*906the roof of his mother’s house, where he began running around, striking the skylight, and screaming. McClenahan’s mother phoned the local police. The 14-day detention petition alleged:
Respondent was detained due to increasingly bizarre behavior, some of which put his health and safety at risk. Since his admission to N.S. E&T [North Sound Evaluation and Treatment] he has continued to exhibit symptoms of psychosis— delusional ideation, tangential and pressured speech, markedly impaired insight. He has no clear and reasonable plans for self care if discharged. Respondent is gravely disabled due to a mental disorder, and there are no less restrictive options at this time.
Clerk’s Papers at 4-5. The petition was signed by Bruce Work and Dr. Dennis Gaither.
The probable cause hearing took place on March 21, 1997. Work testified he had reviewed McClenahan’s chart, spoken with staff and with Dr. Gaither, met with McClenahan, spoken with McClenahan’s mother, and spoken with a friend of McClenahan’s. Over McClenahan’s objection, Work opined McClenahan suffered from a mental disorder called psychotic disorder, NOS (Not Otherwise Specified). McClenahan testified on his own behalf and claimed he was on the roof effecting roof repairs. The trial court found Mc-Clenahan to he suffering from a mental disorder and also to be gravely disabled. The trial court ordered the 14-day commitment.
C. INVOLUNTARY COMMITMENT OF ELLEN LUCAS An Oak Harbor police officer requested a mental health evaluation of Ellen Lucas after her roommates reported to the police officer Lucas had voiced suicidal intentions. The Island County CDMHP evaluated Lucas and reported in the Notice of Emergency Detention:
I began by informing the respondent of her rights. She spoke to me for about two minutes (during which time she asked me for the definition of a pathological liar) and then stated she did [907]*907not want to talk any longer. She sat rigidly, staring blankly and refusing to talk. She then stood up, opened a drawer, took out a large knife, and walked back to her room. I alerted the officer (standing outside) who, along with respondent’s roommates, wrestled the knife away from the respondent. The respondent [missing text] but instead of going to police station, respondent went home.
Based on the respondent’s unwillingness to comply with a less restrictive alternative, her past history of psychotic symptoms, her current presentation and her dangerous behavior (grabbing the large knife and running to her room), this writer is detaining her to N. Sound E&T as danger to self.
Clerk’s Papers 1-2. Two days into Lucas’s detention, on March 14, 1997, Bruce Work completed a 14-day confinement petition concerning Lucas. He signed it as the petitioner, and indicated in the physician’s signature space, as he had with Sheldon’s petition of the same day, “in expectation of psychiatrist’s affidavit.” Clerk’s Papers at 6-8. In the petition, Work detailed the following facts:
Respondent was detained after making suicidal statements and attempting to cut or stab herself with a knife. Since admission to the E&T she has continued to appear quite depressed. Her statements are focused on feelings of hopelessness, helplessness, and self-deprecation. She has great difficulty staying on track and focusing on the present, and has no clear plans for discharge. She reports suicide ideation and anger at friends for taking knife from her. Respondent suffers from a mental disorder which causes her to be a danger to herself. There are no less restrictive alternatives. Clerk’s Papers at 6-7.
Lucas’s probable cause hearing occurred immediately after Sheldon’s hearing on Monday, March 17, 1997. As in Sheldon’s case, Dr. Kathryn Neracs filed an affidavit on the day of the hearing after having met with Lucas and completed the affidavit on the preceding Friday. She did not evaluate Lucas and complete her affidavit until after the State had filed the petition. Dr. Neracs averred:
I am a psychiatrist at North Sound E&T. I have evaluated [908]*908Ellen Lucas today, 3/14/97. Ms. Lucas was detained as DTS [danger to self] after making suicidal statements and attempting to cut or stab herself with a knife. Prozac was started for her depression, however this takes time to work. She remains very depressed. She is tearful, speaks very slowly, and has trouble staying on track with her thoughts. She continues to have suicide ideation. I believe she needs longer hospitalization for further stabilization of her symptoms.
Clerk’s Papers at 15.
During the hearing, a psychiatric counselor from North Sound E&T Facility testified Lucas, in custody, had tried to cut her wrist with a comb by sawing away until all the teeth of the comb had broken off. Work testified, over Sheldon’s objection as to his qualifications, that Lucas suffered from a mental disorder, Psychotic Disorder NOS. He urged her detention for 14 days for further treatment. Lucas presented no witnesses and conceded she suffered from a mental disorder. (“We have not put on any testimony and would concede there is a mental disorder.”). Id. at 14. She argued she was not a substantial risk to herself because the only recent dangerous act she had engaged in, sawing her arm with a comb, did not produce any blood. The trial court ordered the 14-day additional treatment, finding because of her suicidal ideation and attempting to cut herself with the comb, Lucas presented the likelihood of serious harm to herself.
All three individuals sought review of their 14-day confinement orders by the Court of Appeals. That court consolidated the appeals and held the appeals were not moot, the absence of two signatures on the 14-day confinement petitions in the cases of Sheldon and Lucas was not fatal under the particular circumstances of those cases, and a social worker was not disqualified as a matter of law from testifying at a 14-day commitment hearing to the existence of a patient’s mental disorder. In re Detention of A.S., 91 Wn. App. 146, 955 P.2d 836 (1998) (affirming confinement [909]*909orders). The three individuals petitioned for review of that decision, which we granted.
ANALYSIS
A. COMMITMENTS UNDER CHAPTER 71.05 RCW
Before addressing the specific issues in this case, it is useful to consider the provisions of Washington’s Act to place those issues in appropriate context. In 1973, the Legislature enacted the Act to provide specific procedural protections for mentally ill persons subject to involuntary mental treatment. RCW 71.05.030 (“Persons suffering from a mental disorder may not be involuntarily committed for treatment of such disorder except pursuant to provisions of this chapter[.]”) (Laws of 1973, 1st Ex. Sess., ch. 142, § 8). Two of the intentions of the Legislature were to end “inappropriate, indefinite commitment of mentally disordered persons” and to “safeguard individual rights[.]” RCW 71.05.010(1), (3). The Act permits the emergency detention of persons for a 72-hour period upon the filing of a Notice of Emergency Detention by a county designated mental health professional. RCW 71.05.150. RCW 71.05.160 requires:
If a person is involuntarily placed in an evaluation and treatment facility pursuant to RCW 71.05.150, on the next judicial day following the initial detention, the county designated mental health professional shall file with the court and serve the designated attorney of the detained person the petition or supplemental petition for initial detention, proof of service of notice, and a copy of a notice of emergency detention.
If the State wants to hold a person beyond this initial period, it must file a petition in superior court:
The professional staff of the agency or facility or the county designated mental health professional has filed a petition for fourteen day involuntary detention or a ninety day less restrictive alternative with the court. The petition must be signed either by two physicians or by one physician and a [910]*910mental health professional who have examined the person. If involuntary detention is sought the petition shall state facts that support the finding that such person, as a result of mental disorder, presents a likelihood of serious harm, or is gravely disabled and that there are no less restrictive alternatives to detention in the best interest of such person or others. The petition shall state specifically that less restrictive alternative treatment was considered and specify why treatment less restrictive than detention is not appropriate. If an involuntary less restrictive alternative is sought, the petition shall state facts that support the finding that such person, as a result of mental disorder, presents a likelihood of serious harm, or is gravely disabled and shall set forth the less restrictive alternative proposed by the facilityL]
RCW 71.05.230(4). A hearing must then be held at which the State bears the burden of proving by a preponderance of the evidence the statutory grounds for commitment. The individual subject to detention has the right to counsel at such hearing and may compel the attendance of witnesses. RCW 71.05.200, .250. The court may order 14 more days of confinement or 90 days of less restrictive mandatory treatment at the conclusion of such a hearing:
At the conclusion of the probable cause hearing, if the court finds by a preponderance of the evidence that such person, as the result of mental disorder, presents a likelihood of serious harm, or is gravely disabled, and, after considering less restrictive alternatives to involuntary detention and treatment, finds that no such alternatives are in the best interests of such person or others, the court shall order that such person be detained for involuntary treatment not to exceed fourteen days in a facility certified to provide treatment by the department.
RCW 71.05.240. Should the State seek additional commitment of the individual, the burden escalates to proof by clear, cogent, and convincing evidence and the person has the right to a jury trial. RCW 71.05.310, .320. Also, when the State petitions for a 90-day commitment, the court, if requested, shall appoint a “licensed physician, psycholo[911]*911gist, or psychiatrist, designated by the detained person to examine and testify on behalf of the detained person.” RCW 71.05.300. Thus, a person subject to commitment receives ever-increasing procedural rights as the commitment duration lengthens.
In 1979, the Legislature amended the Act to allow for involuntary treatment of persons who were “gravely disabled,” persons who are in danger of serious physical harm resulting from a failure to provide for essential human health or safety needs as a result of a mental disorder. RCW 71.05.020(1), enacted by Laws of 1973, 1st Ex. Sess., ch. 142, § 7. See In re Detention of LaBelle, 107 Wn.2d 196, 728 P.2d 138 (1986) (upholding constitutionality of “gravely disabled” statute).
We have previously indicated the appropriate interpretative principles to be employed in reviewing the Act:
where as here a significant deprivation of liberty is involved, statutes must be construed strictly. In re Cross, 99 Wn.2d 373, 379, 662 P.2d 828 (1983). On the other hand, our primary objective in interpreting a statute is to ascertain and give effect to the intent of the Legislature. State v. Keller, 98 Wn.2d 725, 728, 657 P.2d 1384 (1983). In so doing, the spirit and intent of the law should prevail over the letter of the law. In re R., 97 Wn.2d 182, 187, 641 P.2d 704 (1982). Furthermore, we will construe a statute so as to avoid strained or absurd consequences which could result from a literal reading. State v. Keller, supra.
LaBelle, 107 Wn.2d at 205.
In the present case, we note none of the three individuals sought to compel the attendance of Drs. Gaither or Neracs at their 14-day confinement hearing. Nor did any of them present testimony from their own mental health professionals. We now turn to the two issues present in this case.
B. THE VALIDITY OF THE PETITIONS
Sheldon and Lucas assert the petitions for 14-day invol[912]*912untary treatment the State filed were invalid and should have been dismissed because they were not signed by a physician. RCW 71.05.230(4) provides in pertinent part: “The petition must be signed either by two physicians or by one physician and a mental health professional who have examined the person.” The regular staff psychiatrist at North Sound E&T where Sheldon and Lucas were detained, Dr. Gaither, who had earlier examined them, was ill and not present to sign the petitions on the day the State filed them. Bruce Work, who did sign both petitions, indicated in the signature block for the physician an affidavit from a psychiatrist would follow. At the probable cause hearing, the State offered the affidavits of Dr. Neracs as a substitute for the signature of the psychiatrist on the petition. Dr. Neracs averred in her affidavits there was justification for the detention and involuntary treatment of both Sheldon and Lucas.
Sheldon and Lucas now argue the involuntary commitment statute must he strictly construed, correctly citing LaBelle, 107 Wn.2d at 205 (holding statutory criteria for finding person “gravely disabled” not unconstitutionally vague). Strict construction, they maintain, must result in dismissal of the petitions if they are not signed by either two physicians or by one mental health professional and one physician, pursuant to the statute.
The Court of Appeals disagreed. It held the failure to obtain the physician’s signature on the petitions was not fatal because the physician’s affidavits attesting to the need for additional treatment were available to the trial court at the time of the probable cause hearings. As a result, the statutory requirement for two qualified persons to attest to the need for a hearing regarding further treatment was fulfilled. Essentially, although the Court of Appeals did not use the term, there was substantial compliance here with the legislative intent. Detention of A.S., 91 Wn. App. at 158-59.
The Court of Appeals was correct. The Legislature listed in RCW 71.05.010 the following items as part of its intent in enacting chapter 71.05 RCW:
[913]*913(1) To prevent inappropriate, indefinite commitment of mentally disordered persons and to eliminate legal disabilities that arise from such commitment;
(2) To provide prompt evaluation and timely and appropriate treatment of persons with serious mental disorders;
(3) To safeguard individual rights;
(4) To provide continuity of care for persons with serious mental disorders;
(5) To encourage the full use of all existing agencies, professional personnel, and public funds to prevent duplication of services and unnecessary expenditures; . . .
The intent of the Act is implemented by allowing these petitions to proceed. The circumstances here were unique. First, Sheldon and Lucas unquestionably were troubled and mentally disordered; there is no question here about callous or oppressive mental health officials locking people up for specious reasons in the guise of treatment. Second, the absence of a physician’s signature on the petitions was not the result of oppression, carelessness, or attempted circumvention of the statutory procedural requirements, but rather resulted from the illness of the physician who performed Sheldon’s and Lucas’s intake evaluations, Dr. Gaither, who, because of his illness, was not available to sign the petitions. To make up for Dr. Gaither’s absence, another physician, Dr. Neracs, was summoned from Seattle to evaluate Sheldon and Lucas and provide support for the 14-day confinement petitions. Because she was summoned on short notice, Dr. Neracs was not able to complete the evaluations and sign the petitions before they were filed, so she provided affidavits as substitutes.
Third, even if the petitions were improper, the petitions would only have been dismissed without prejudice. In re Detention of J.R., 80 Wn. App. 947, 953-54, 912 P.2d 1062, review denied, 130 Wn.2d 1003, 925 P.2d 989 (1996). At the time the individuals raised the issue, the State had sufficient time under the statute to file corrected petitions and new probable cause hearings could have been held. No [914]*914prejudice to the individuals occurred here, as counsel conceded in oral argument.4 See In re Detention of G.V., 124 Wn.2d 288, 877 P.2d 680 (1994) (abuse of discretion to deny State one day continuance to advise patients of right to refuse medications where recommitment hearings could be timely held despite continuance).
Finally, Sheldon’s and Lucas’s rights were not compromised in these cases. Their detention was commenced by the filing of the notice of emergency detention, about which they do not complain, not the filing of the 14-day confinement petition. The additional 14-day confinement came about only after their probable cause hearings and the trial court’s orders detaining them for 14 days of involuntary treatment. Thus, the lack of signatures on their petitions did not cause an “inappropriate” commitment. Nor were they deprived of due process; they had both notice and an opportunity to be heard, the cornerstones of due process.5 Their objections are formal, not substantive, and should be rejected. See Crosby v. County of Spokane, 137 Wn.2d 296, 971 P.2d 32 (1999) (substantial compliance with legislative intent surmounts even jurisdictional hurdle).6
[915]*915C. ADMISSIBILITY OF SOCIAL WORKER’S OPINION TESTIMONY
All three individuals argue Bruce Work was not qualified to opine they suffered from a mental disorder, meaning “any organic, mental, or emotional impairment which has substantial adverse effects on an individual’s cognitive or volitional functions[.]” RCW 71.05.020(15). In the DSHS regulation, “ ‘Mental disorder’ means any organic, mental, or emotional impairment having substantial adverse effects on an individual’s cognitive or volitional functions, classified in accordance with the current diagnostic and statistical manual of the American psychiatric association.” WAC 275-55-020(17).
They also assert only physicians and psychiatrists are qualified to diagnose mental disorders. They do not offer the opinion of a physician or psychiatrist to support their contention. Nor do they point to a statute or regulation stating as much. They argue expert opinion testimony concerning a person’s mental status is not admissible unless the expert holds his or her opinion with reasonable medical or psychological certainty. In re Detention of Twining, 77 Wn. App. 882, 891, 894 P.2d 1331, review denied, 127 Wn.2d 1018, 904 P.2d 299 (1995). Because Work is neither a medical doctor nor a psychologist, they contend, he cannot possibly hold any opinion with a reasonable degree of medical or psychological certainty.7
The individuals also make a statutory argument. They note the Legislature enacted licensure for social workers, mental health counselors, and marriage and family therapists in 1987, Laws of 1987, ch. 512, but later amended the statutes pertaining to the latter two categories of profes[916]*916sionals specifically to authorize them to diagnose mental disorders. Laws of 1995, ch. 183, § 1; Laws of 1993, ch. 259, § l.8 Because the Legislature did not amend the scope of practice for social workers to include diagnosing mental [917]*917disorders, the individuals assert the negative inference must mean the Legislature considers such diagnoses beyond the scope of social worker practice. We treat each argument in turn.
Our analysis of the admissibility of expert opinion evidence begins with ER 702 and 703. ER 702 provides:
If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.
Similarly, ER 703 states:
The facts or data in the particular case upon which an expert bases an opinion or inference may be those perceived by or made known to the expert at or before the hearing. If of a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject, the facts or data need not be admissible in evidence.
Moreover, the long-standing rule in Washington is, “Qualifications of expert witnesses are to be determined by the trial court within its sound discretion, and rulings on such matters will not be disturbed unless there is a manifest abuse of discretion.” Oliver v. Pacific Nw. Bell Tel. Co., 106 Wn.2d 675, 683, 724 P.2d 1003 (1986).
Initially, there is nothing in the professional licensure statute for social workers that bars a social worker from giving an opinion on the existence of a mental disorder. Indeed, RCW 18.19.110(3) provides: “Certified social work practice . . . includes, but is not limited to, evaluation, assessment, treatment of psychopathology, consultation, psychotherapy and counseling . . . directed toward client services.” (Emphasis added.) The rendering of an opinion on the existence of a mental disorder was clearly within [918]*918this statutory description of social worker’s scope of practice. The Legislature did not need to amend the social worker scope of practice as originally enacted in 1987 because it plainly allowed social workers to diagnose mental disorders.
Moreover, there is nothing in chapter 71.05 RCW itself that bars a social worker from testifying to the presence of a mental disorder. To the contrary, RCW 71.05.020(16) states: “ ‘Mental health professional’ means a psychiatrist, psychologist, psychiatric nurse, or social worker, and such other mental health professionals as may be defined by rules adopted by the secretary [of the Department of Social and Health Services] pursuant to the provisions of this chapter[.]” A social worker who is trained as a mental health professional is entitled to serve as a CDMHP who may detain individuals on an emergency basis, RCW 71.05.150, and to sign a petition for a 14-day confinement. RCW 71.05.230. It would be entirely anomalous for the Legislature to authorize a person to detain an individual for a mental disorder and sign the petition for that individual’s lengthier commitment, but then bar that person because of a lack of qualifications from testifying at a hearing concerning the detained individual’s mental disorder.
Finally, any reliance on Twining, a case involving the commitment of sexually violent predators, is misplaced. A social worker is not obliged to testify to a reasonable medical or psychological certainty as to a mental disorder, but only to reasonable professional certainty. As the Court of Appeals persuasively noted, “[petitioners] misconstrue this standard, which does not measure the expert’s qualifications, but rather the correlation between the facts and the expert’s opinion.” Detention of A.S., 91 Wn. App. at 160. We decline to hold a social worker is categorically barred from testifying to the existence of a mental disorder.
This view is consistent with the law in other jurisdictions. In New York, “Properly trained clinical social workers are manifestly competent to diagnose mental disorders.” [919]*919People v. Scala, 128 Misc. 2d 831, 491 N.Y.S.2d 555, 560 (Sup. Ct. 1985). As a New York Supreme Court explained:
With regard to the question of whether or not a non-medical mental health professional may diagnose mental disorders and provide an expert opinion as to that diagnosis, I note that clinical social work, as a profession, is one of the core mental health disciplines. As are psychiatrists and clinical psychologists, clinical social workers are skilled in the diagnosis and treatment of mental disorders. Psychiatrists, who are physicians, bring their expertise in the understanding of organic pathology, psychopharmacology and other somatic treatments to the mental health field. Clinical psychologists, being scientists who study human behavior as well as being non-medical mental health professionals, bring their particular skills in research and in the study of behavior to the mental health field. It can be noted that clinical social workers, also non-medical mental health professionals, bring their expertise in dealing with the relationship between social and emotional functioning as well as their expertise in social policy and in environmental intervention to the mental health field.
The Diagnostic and Statistical Manual of Mental Disorders—Third Edition (DSM III) represents the current guide for the diagnosis of mental disorders in the United States. The diagnostic criteria set forth in the DSM III were validated during field trials. These field trials were carried out by professionals from the disciplines of Psychiatry, Psychology, Clinical Social Work and Psychiatric Nursing. Besides psychiatrists, psychologists and clinical social workers served on several of the advisory committees which developed this diagnostic guide and served as consultants to the task force which compiled it. This court is informed that a social worker, Janet Williams, M.S.W., served as Co-principal Investigator and Project Coordinator for the reliability study and field trials of the DSM III. Further, throughout the DSM III references are made to its utilization by “clinicians”, not exclusively by psychiatrists. It is clear, that if one is to accept the DSM III as a valid and reliable guide, then one must accept that properly trained psychiatrists, psychologists, clinical social workers and psychiatric nurses are qualified to apply its diagnostic criteria in their diagnostic assessment of patients. I find no merit in any arguments that the application and use of the DSM III diagnoses should be limited to physicians and psychiatrists.
[920]*920This court holds that even though they are not physicians, certified social workers who demonstrate appropriate training and supervised clinical experience in the diagnostic assessment of mental disorders may, within the scope of their license, make diagnostic assessments of a person’s mental condition and may qualify as experts in the diagnosis of mental disorders.
People v. Gans, 119 Misc. 2d 843, 465 N.Y.S.2d 147, 148-49 (Sup. Ct. 1983).
The petitioners cite three cases in their supplemental brief for the proposition, “Courts in other jurisdictions likewise agree that a social worker is unqualified to give a ‘medical diagnosis.’ ” Supplemental Br. of Pet’rs at 10. This statement is incorrect; the cases cited do not come close to standing for that proposition. For instance, the petitioners say People v. Skowronski, 61 Mich. App. 71, 232 N.W.2d 306 (1975), speaks to “Michigan’s well-established rule that social workers are unqualified to testify as an expert to evaluate competency.” Supplemental Br. of Pet’rs at 12-13. What that case actually says is this:
The trial court erred in allowing a social worker to testify as an expert to evaluate competency. The forensic center had administered several psychological tests and reported there was no evidence of organic brain damage. However, the only witness provided at the competency hearing by the forensic center was a social worker who admitted she was not qualified to administer or evaluate those tests.
Skowronski, 232 N.W.2d at 310. This is a far cry from the petitioners’ assertion that social workers are unqualified to give a medical diagnosis. Similarly, petitioners cite United States v. Moses, 137 F.3d 894 (6th Cir. 1998), for the proposition “the social worker did not qualify as an expert for purposes of rendering a psychological or psychiatric opinion under the Act.” Supplemental Br. of Pet’rs at 11. That is not what the case held. The issue in Moses was whether the social worker could testify as to the trauma a child abuse victim would undergo by testifying in open court. The Court of Appeals reversed the trial court’s admission of a social worker’s testimony about trauma not because [921]*921social workers are generally unqualified to give such opinions, but because the particular social worker in that case did not have “any ‘special skill or knowledge’ generally relating to trauma.” In addition, the social worker had testified in court only twice before, and only once in a case involving child sexual abuse. Moses, 137 F.3d at 900. The court made no general statement disqualifying social workers from giving trauma testimony; indeed, the negative implication of the court’s opinion is a properly qualified and experienced social worker could have given such testimony. Finally, petitioners cite Vallinoto v. DiSandro, 688 A.2d 830 (R.I. 1997), in which the court held a social worker could not testify a client suffered from posttraumatic stress disorder, as that disorder could be diagnosed only by medical experts. Vallinoto announced no general rule forbidding social workers from testifying about mental disorders. It merely said posttraumatic stress disorder is a medical condition and the social worker did not present any qualifications for making such a diagnosis. There is no showing here that the statutorily defined term, “mental disorder,” is a medical condition only a physician can diagnose.
In the present case, applying the principles of ER 702 and 703, the trial court did not abuse its discretion in finding Work qualified as an expert and in admitting his opinion on the mental disorders of Sheldon, McClenahan, and Lucas. Work met the statutory definition of a social worker. “ ‘Social worker’ means a person with a master’s or further advanced degree from an accredited school of social work or a degree deemed equivalent under rules adopted by the secretary[.]” RCW 71.05.020(25). He was licensed under chapter 18.19 RCW as well. Work was the CDMHP for Thurston and Grays Harbor Counties. He had performed thousands, of mental health evaluations. Work appropriately qualified as an expert.
As to the three individuals here, Work testified that in preparation for his testimony at both the Sheldon and the McClenahan probable cause hearings he reviewed the charts, spoke with Dr. Gaither, spoke with the staff, spoke [922]*922with Sheldon’s wife by phone, interviewed both Sheldon and McClenahan, and spoke with the detaining mental health professionals. The chart Work relied upon contained Dr. Gaither’s “fairly long assessment” of Sheldon, which Dr. Gaither prepared upon Sheldon’s initial confinement on March 12, 1997. Work was qualified as a mental health professional, and he relied in part on his opinion of the diagnosis of a psychiatrist, Dr. Gaither. His testimony was therefore admissible under ER 703.
In summary, social workers in their statutorily defined roles as mental health professionals and CDMHPs occupy central positions in the care and treatment of those subject to involuntary commitment for mental disorders. They are one of two permitted signatories to the 14-day petition for involuntary treatment. The Legislature plainly contemplated they would be qualified to testify about their reasons for signing the petition. The statute defining certified social workers includes psychopathology and psychotherapy within a social worker’s scope of practice. In the absence of legislative direction limiting a social worker’s scope of practice, or defining “mental disorder” under chapter 71.05 RCW as a condition only a physician may diagnose, we decline to formulate a categorical evidentiary rule. Rather, we continue to allow trial courts to exercise their sound discretion as to a social worker’s qualifications to opine about mental disorders.9
CONCLUSION10
The 14-day confinement petitions for Sheldon and Lucas, [923]*923though lacking a second signature, were sufficient under these unique circumstances insofar as a physician submitted an affidavit in support of the petition at the time of the hearing. These individuals were not prejudiced by the absence of a physician’s signature.
Moreover, in the absence of expert testimony that determination of a mental disorder is beyond the scope of a social worker’s practice under chapter 18.19 RCW or a legislative declaration in chapter 71.05 RCW that only physicians may offer expert testimony as to the existence of a mental disorder, we decline to make a categorical rule that a social worker, no matter how qualified by training and experience, may never opine about a person’s mental disorder. We instead uphold the usual rule that admission of expert testimony is within the sound discretion of the trial court, governed by ER 702 and 703, and will be overturned only for manifest abuse of discretion. The trial court did not abuse its discretion in these cases by allowing Bruce Work to testify. We affirm the Court of Appeals and the trial court’s 14-day confinement orders.
Guy, C.J., and Durham, Smith, and Ireland, JJ., concur.
.
3Work testified: “It was not my observation that that was the case. That in fact he could read things, and he held them up close directly in from of him. Also his eye contact with me was good, which would suggest that blindness was probably not likely.” Report of Proceedings at 22.