dissenting:
Although I agree with the majority that, for purposes of section 8-41-301, 3 C.R.S. (2003), “mental impairment” need only be supported- — and not necessarily “proved”— by the testimony of a physician or psychologist, I conclude that the entirety of the statute’s definition of “mental impairment” is subject to that requirement. Because I would not limit the statute’s evidentiary requirement to selected elements of the statute’s “mental impairment” definition alone, I respectfully dissent. I would, therefore, affirm the court of appeals’ decisions in both of these cases.
I. Facts
A. Davison v. ICAO
The first case in this appeal involves workers’ compensation benefits sought by the widow of Captain David Davison following his suicide. At the time of Captain Davison’s death, he was in charge of the Services Division of the Loveland Police Department (the “Department”). This responsibility entailed a significant amount of personnel work in the Department. Captain Davison had assumed this particular position about four months before he died.
In the years leading up to his death, Captain Davison had experienced a number of unfortunate heartaches, both personal and professional. In April, 1994, his brother died unexpectedly and in October, 1995, his wife was diagnosed with a life-long illness. On or about April 4, 1996, Captain Davison and his supervisor, Chief of Police Tom Wagoner, discovered that several officers, while they were pursuing a sting operation regarding a prostitution ring, had engaged in sexual acts with the prostitutes they were investigating. The incident attracted a significant amount of media attention.
On April 11, 1996, Captain Davison was given the responsibility of disciplining the officers that had acted inappropriately during the sting. After Captain Davison had expressed misgivings about handling the discipline process alone, Chief Wagoner agreed to share the responsibility. Then, troubled by the mounting stresses of his job, and suffering severe psychotic depression, Captain Davison took his own life on April 16, 1996.
Shortly after Captain Davison’s suicide, his widow, Lana Lea Davison, filed a claim for workers’ compensation benefits, asserting that her husband’s psychological injury and resulting suicide were caused by job-related stress, generally compensable under workers’ compensation provisions. At an adminis*1034trative hearing on her claim before an administrative law judge (ALJ), Davison presented the testimony of Dr. Robert David Miller, a licensed psychiatrist. Dr. Miller testified that Captain Davison had been suffering from depression for about four or five years before his death and that the stress from his job was the main cause of that death. The ALJ approved the .claim and made findings under section 8-41-301 — the statutory section that ■ itemizes the “conditions of recovery” for an injury of this type. The ALJ determined that Captain Davison’s “depression was principally caused by the stress of his job at the [Loveland Police Department, and t]he type of job pressures experienced by the captain were unique, outside a worker’s usual experience, and would evoke significant symptoms of distress in a worker in similar circumstances.”
Upon appeal, the Industrial Claims Appeal Office (ICAO) reversed the ALJ’s decision, concluding that Davison had failed to produce testimony of a licensed physician or psychologist showing that her husband’s injury consisted of “a psychologically traumatic event that is generally outside of a worker’s usual experience and would [have evoked] significant symptoms of distress in a worker in similar circumstances,” as required by section 8-41-301(2)(a).
On appeal to the court of appeals, Davison argued that physicians and psychologists are not capable of testifying as to that portion of the statute, and, hence, section 8-41-301(2)(a) should not be read to require such testimony. The court of appeals affirmed the ICAO’s reversal, stating that “[b]eeause we cannot say that such topics are necessarily beyond the expertise or specialized knowledge of physicians or psychologists, we apply the statute as written.” Damson v. ICAO, 72 P.3d 389, 391 (Colo.App.2003). Davison appeals to this court, arguing that the court of appeals erred in its interpretation of section 8-41-301(2)(a).
B. Mobley v. ICAO
Aso included in this consolidated opinion is the appeal of Cheryl Mobley, who had worked as a pharmacist at King Soopers for nearly twenty years before her employment was. terminated. On August 21, 1997, Mob-ley was summoned to a disciplinary meeting with the store manager and two security officers to discuss possible “time card irregularities.” Mobley claims that she was “bumped” by one of the attending security officers on the way to the meeting and that during the meeting, she was made to feel intimidated and isolated. After Mobley requested union representation, the manager ended the meeting because he could not locate a union representative in time. After the meeting, Mobley did not return to work.
Shortly after the incident, Mobley saw a psychiatrist, Dr. Fuller, vyho diagnosed her with “single episode depression.” Dr. Fuller determined that the condition resulted from Mobley’s employment and restricted her from working at King Soopers. Mobley later filed a claim for workers’ compensation benefits on the basis of a work-related mental impairment.
Hearings on Mobley’s claim began on January 22, 2001. On July 17, 2001, the ALJ held that Mobley’s case-in-chief was closed, except that the ALJ agreed to consider specific evidence from an arbitration hearing that addressed whether Mobley was wrongfully discharged under a collective bargaining agreement. King Soopers then moved to dismiss the claim on the grounds that Mobley had failed to introduce any testimony by a physician or psychologist showing that the incident allegedly causing her depression would “evoke significant symptoms of distress in a worker in similar circumstances.” The ALJ agreed and dismissed the claim.
Mobley appealed the ALJ’s dismissal to the ICAO. The ICAO agreed with the ALJ that the statute required Mobley to submit testimony, as that term is understood in Colo. Dep’t Of Labor and Employment v. Esser, 30 P.3d 189 (Colo.2001), of a licensed physician or psychologist, supporting the conclusion that the event in question would “evoke significant symptoms of distress in a worker in similar circumstances.” Accordingly, the ICAO upheld the ALJ’s dismissal.
On appeal to the court of appeals, Mobley argued that the ICAO had erroneously interpreted section 8-41-301(2)(a)’s evidentiary *1035requirement. The court of appeals, however, upheld the ICAO’s ruling in an unpublished opinion and this appeal ensued.
II. Analysis
Section 8-41-301(2)(a) states in pertinent part that
[a] claim of mental impairment must be proven by evidence supported by the testimony of a licensed physician or psychologist. For purposes of this subsection (2), “mental impairment” means a recognized, permanent disability arising from an accidental injury arising out of and in the course of employment when the accidental injury involves no physical injury and consists of a psychologically traumatic event that is generally outside of a worker’s usual experience and would evoke significant symptoms of distress in a worker in similar circumstances.
(emphasis added). Mobley and Davison (Petitioners) do not dispute that a plain reading of this statute requires physician or psychologist testimony to support the first part of the statute’s definition — “a recognized, permanent disability arising from an accidental injury arising out of and in the course of employment when the accidental injury involves no physical injury.” However, they would have this court draw a line in the statute, eliminating any requirement that a physician’s or psychologist’s testimony support the rest of the statute’s “mental impairment” definition. Petitioners argue it would be illogical to require medical testimony for the remaining portion of the statute’s definition because, they contend, whether an event is outside of a worker’s usual experience and would evoke significant symptoms of distress in a similarly situated worker is only susceptible to proof by non-medical testimony. Specifically, Mobley argues that a “disability,” of which “mental impairment” is an example, can only be proved through non-medical means. However, no one disputes that Mobley’s mental impairment is disabling— only whether her particular disability is a compensable “mental impairment” under section 8-41-301.
Davison contends that a plain reading of the statute requires only that expert medical testimony “support” a finding of mental impairment in the sense that the medical testimony must support at least some part — but not all — of the statutory definition of “mental impairment.”
A. Expert Testimony Need Only “Support” — and Not Necessarily “Prove”— “Mental Impairment”
I agree with the majority that in order to prove a “mental impairment” for purposes of section 8-41-301, a claimant need only present the testimony of a licensed physician or psychologist that tends to support a finding of “mental impairment,” as defined in the statute. The first sentence of section 8-41-301(2)(a) states that “[a] claim of mental impairment must be proven by evidence supported by the testimony of a licensed physician or psychologist.” (emphasis added). As the majority correctly notes, a plain reading of this first sentence indicates that the evidence used to prove a claim of mental impairment need only be supported by — rather than wholly consist of — expert medical testimony. This standard allows a plaintiff to carry her burden of proof with non-expert evidence, for example, as to the nature of her employment and whether the injury occurred in the course of employment, while still requiring expert testimony to buttress the claim in order to prevent recovery on frivolous claims, Oberle v. ICAO, 919 P.2d 918, 920 (Colo.App.1996).
B. Expert Medical Testimony Required to Prove the Entire Statutory Definition of “Mental Impairment”
However, the majority reads the statute to require expert medical testimony only as to some elements of mental impairment and not as to others. Maj. Op. at 1031-1032. Contrary to the majority, I do not view section 8-41-301(2)(a)’s evidentiary requirement as permitting that selective approach. Rather, I would begin by noting the statute’s obvious purpose: namely, to prevent frivolous claims related to mental injury brought on by emotional trauma that are not subject to direct proof, Tomsha v. City of Colo. Springs., 856 P.2d 13, 15 (Colo.App.1992). The plain language of section 8-41-301(2)(a) clearly re*1036quires medical expert testimony to support a finding of “mental impairment” as defined by 8-41-301(2)(a) and makes no distinction among the elements of mental impairment that must be so supported.
As in construing any statute, this court must give effect to legislative intent and we must do so by first applying the plain language of the statute. Colo. Dep’t of Revenue v. Gamer, 66 P.3d 106, 109 (Colo.2003). We must also construe all terms of a statute harmoniously, avoiding a strained or forced construction of any of its terms. Fogg v. Macaluso, 892 P.2d 271, 274 (Colo.1995). Only when the statute is ambiguous should we resort to other principles of statutory construction. DeHerrera v. Sentry Ins. Co., 30 P.3d 167, 171 (Colo.2001); Vaughan v. McMinn, 945 P.2d 404, 408 (Colo.1997). Under no circumstances may we write provisions into statutes that were clearly not intended by the legislature. Schlessinger v. Schlessinger, 796 P.2d 1385,1389 (Colo.1990).
The issue before the court in these cases is simply whether a claimant must introduce expert testimony in support of the “second clause” of the definition of “mental impairment” whether the injury “consists of a psychologically traumatic event that is naturally outside of a worker’s usual experience and would evoke significant symptoms of distress in a worker in similar circumstances.” Davi-son’s and Mobley’s claims were dismissed specifically because they failed to introduce expert testimony on that portion of the statutory definition.
I first take issue with the claimants’ argument that the sentence can be bifurcated into a “first clause” and a “second clause.” The “second clause” begins in the middle of a single descriptive phrase — “a recognized, permanent disability arising from an accidental injury arising out of and in the course of employment when the accidental injury involves no physical injury and consists of a psychologically traumatic event.” § 8-41-301(2)(a)(emphasis added). In my view, neither the language nor the grammatical construction of the statute would support an interpretative division that would invoke expert testimony as to a portion of the phrase and not as to the balance.
Based in part upon that interpretive division in the statute, the majority concludes generally that expert testimony under the statute is limited to concepts that fall within the purview of a licensed physician’s or psychologist’s expertise, and specifically that the question about whether the injury at issue would cause a similar reaction to a similarly situated worker is outside of that rubric. I disagree both with the statutory interpretation, and also with the practical application. Like the court of appeals, I see no reason to assume that any physician or psychologist will be unable, upon a reasonable investigation, to testify as to whether the injury at issue consists of a psychologically traumatic event that is outside of a worker’s usual experience or whether that event would cause distress to other similarly situated workers, or even whether the injury arose out of or in the course of employment. Indeed, particularly the question of whether the event would cause distress to another worker under similar circumstances seems to me to be outside .the knowledge or common experience of the ordinary lay witness and, therefore, seems to demand an expert opinion. See Zick v. Krob, 872 P.2d 1290, 1294 (Colo.App.1993). I cannot conceive how a claimant would prove that an injury consists of a psychologically traumatic event and also that it would cause distress in other similarly situated workers without the help of expert testimony.
The entire statute contains an intermixture of factual conclusions and professional opinions. If the legislature had intended for the statute’s terms to carry different evidentiary requirements, it could plainly and easily have expressed this intention.
On the other hand, I also appreciate how it might be difficult for the claimant to meet her burden of proof on some of these matters without resort to non-expert evidence. Yet, this is why the legislature took care to explain that claimants were required only to support the claim of mental impairment with expert testimony — not prove it exclusively by that means.
III. Conclusion
I agree with the court of appeals’ conclusion that the plain language of section 8 — 41-*1037301(2)(a) requires that a claimant present expert medical or psychological testimony to support all of the elements of the statutorily defined term “mental impairment” before she can recover for her “mental-mental” injury. Thus, I would affirm the court of appeals’ decisions in these consolidated cases and accordingly dissent.
I am authorized to state that JUSTICE COATS joins in this dissent.