OPINION
While working as a police officer for the City of Hutchinson, and after responding to an accident, relator Scott B. Schuette developed symptoms that were later diagnosed as post-traumatic stress disorder (PTSD). A compensation judge denied Schuette’s workers’ compensation claim on the ground that Schuette’s PTSD lacked a physical component and thus is not com-pensable. Applying Lockwood v. Independent School District No. 877,
I.
On June 23, 2005, Schuette — then a full-time police officer for the City of Hutchinson (the employer) — responded to an accident at the local high school. A girl had fallen out of a pickup truck. After arriving at the scene, Schuette realized that he knew the victim and her family. Schuette administered CPR and, upon request, drove the victim to the hospital by ambulance.
During a mental health evaluation on June 18, 2008, Schuette was diagnosed with PTSD. Since then, 11 health-care professionals have concurred. Schuette also suffers from chronic back and shoulder pain from a fall during a nightmare. At least one doctor attributes the fall to PTSD.
In 2009, Schuette resigned from his position with the employer. He filed a claim petition seeking workers’ compensation benefits for PTSD under Minn.Stat. § 176.021, subd. 1 (2012). Schuette also sought compensation for the injury to his back and shoulder as a “consequential injury.”
On March 14, 2012, in a hearing before a compensation judge, Schuette argued, with expert support, that PTSD has a dramatic effect on the physical and chemical structure of the brain. According to one of Schuette’s experts, a clinical neuropsychol-ogist, a functional MRI revealed abnormalities in the frontal lobe region of Schuette’s brain. The employer, with support from two experts — one a clinical psychologist and professor in the department of psychiatry and psychology at the University of Minnesota, and the other a board-certified psychiatrist — disagreed. The employer argued that the scientific literature has not established that PTSD causes a physical injury to the brain.
The compensation judge denied Schuette’s claim, finding that Schuette’s PTSD “represents a mental disability.” In so finding, the compensation judge rejected the opinions of Schuette’s experts as unpersuasive and adopted the opinions of the employer’s experts. The compensation judge therefore determined that Schuette’s PTSD is not a compensable personal injury under Minnesota law.
Schuette appealed to the WCCA, which affirmed unanimously. Citing Lockwood, the WCCA noted that a mental injury resulting from mental stimulus is not com-pensable under the Minnesota Workers’ Compensation Act. The WCCA explained that, to be compensable under Lockwood, an injury must include a physical component. The WCCA concluded that the compensation judge’s findings that Schuette’s PTSD did not result in a physical brain injury had substantial evidentiary support.
By writ of certiorari, Schuette sought further review before our court. Schuette maintains that, under Lockwood, he suffered a compensable personal injury. In the alternative, Schuette argues that Lockwood should be overruled, in part because it results in an application of the Minnesota Workers’ Compensation Act that violates his constitutional right to equal protection of the law.
II.
Schuette’s first argument on appeal is that PTSD is a physical brain injury and the compensation judge erred in finding otherwise. But we cannot disturb a compensation judge’s findings affirmed by the WCCA unless the findings are manifestly contrary to the evidence or unless the evidence clearly requires reasonable minds to adopt a contrary conclusion. Hengemuhle v. Long Prairie Jaycees,
Under Minnesota law as of the date of Schuette’s injury, “[ejvery employer ... [was] liable to pay compensation in every case of personal injury or death of an employee arising out of and in the course of employment.” Minn.Stat. § 176.021, subd. 1 (emphasis added). “Personal inju
To clarify the meaning of “personal injury” and “occupational disease” in workers’ compensation cases involving a mental stimulus or a mental injury, our Lockwood decision divided such cases into three categories: (1) cases in which mental stimulus produces physical injury, (2) cases in which physical stimulus produces mental injury, and (3) cases in which mental stimulus produces mental injury. Lockwood,
Because the compensability of a mental injury depends upon the Lockwood category in which the injury falls, medical evidence is of paramount importance. In weighing medical evidence, a compensation judge has the discretion as the trier of fact to choose between competing and conflicting medical experts’ reports and opinions. Ruether v. State,
In this case, the compensation judge’s findings, including the finding that Schuette’s PTSD is a noncompensable mental injury, are not manifestly contrary to the evidence. Schuette is correct that considerable evidence before the compensation judge supported his position that he sustained a physical brain injury. But the compensation judge was free to choose among conflicting medical experts’ opinions, Ruether,
III.
Schuette’s second argument is that our Lockwood decision should be overruled because it improperly excluded mental injury caused by mental stimulus from the statutory term “personal injury.” Schuette also posits that, if Lockwood is not overruled, Minn.Stat. § 176.021, subd. 1, of the Workers’ Compensation Act violates his federal and state equal-protection rights. Questions of law such as this are reviewed de novo. See Roemhildt v. Gresser Cos.,
A.
We decline Schuette’s request to overrule Lockwood, and, necessarily, Johnson, on the theory that these decisions misconstrued the statutory term “personal injury.” The doctrine of stare decisis directs us to adhere to our former decisions in order to promote the stability of the law and the integrity of the judicial process. Seminole Tribe of Fla. v. Florida,
Schuette fails to provide a compelling reason to overrule Lockwood and Johnson. We are as sensitive today as we were in Lockwood that mental injury caused by mental stimulus “is as real as any other kind of disablement.” Lockwood,
B.
We turn next to Schuette’s argument that Lockwood, and, necessarily, Johnson, should be overruled because they result in an application of the Workers’ Compensation Act that violates his right to equal protection of the law. The United States Constitution guarantees that no state will “deny to any person within its jurisdiction the equal protection of the laws.” U.S. Const, amend. XIV, § 1. The Minnesota Constitution guarantees that “[n]o member of this state shall be disfranchised or deprived of any of the rights or privileges secured to any citizen thereof, unless by the law of the land or the judgment of his peers.” Minn. Const, art. I, § 2. Both guarantees “begin with the mandate that all similarly situated individuals shall be treated alike.” Kolton v. Cnty. of Anoka,
We generally assess constitutional challenges to the coverage of workers’ compensation statutes using a form of rational-basis review. Gluba ex rel. Gluba v. Bitzan & Ohren Masonry,
Schuette concedes that the first prong of the applicable rational-basis test is satisfied: the distinction between physical and mental injuries caused by mental stimulus applies uniformly to all those similarly situated. Therefore, the only remaining questions are whether the classification is necessitated by genuine and substantial distinctions between physical and mental injuries and whether the classification effectuates the purpose of the Minnesota Workers’ Compensation Act.
The second prong of our three-part rational-basis test focuses on whether the Legislature “could reasonably have believed in any facts” that would support the challenged workers’ compensation classification. Gluba,
The third and final prong is whether the distinction recognized in Lockwood effectuates the purpose of the Workers’ Compensation Act. At its core, the Workers’ Compensation Act aims “to assure the quick and efficient delivery of indemnity and medical benefits to injured workers at a reasonable cost.” Minn.Stat. § 176.001 (2012). In other words, the Workers’ Compensation Act is premised on a reasonable tradeoff “between workers’ interests on the one hand and employers’ interests on the other.” Gluba,
For these reasons, we hold that the Workers’ Compensation Act applicable to Schuette, as interpreted by Lockwood and Johnson, does not violate his equal-protection rights.
Affirmed.
Notes
. The injuries from the accident Schuette responded to were horrific. While Schuette was administering CPR, the girl’s father put pressure on her ear to stop her spinal fluid from leaking. Schuette later noticed some of the girl's brain matter on his uniform. The girl died from her injuries.
. The 2013 Legislature amended the definition of "personal injury” and "occupational disease” in Minn.Stat. § 176.011, subds. 15-16, to include "mental impairment.” Act of May 16, 2013, ch. 70, art. 2, §§ 1-2, 2013 Minn. Laws 362, 367-68 (to be codified at Minn.Stat. § 176.011, subds. 15(a), (d), 16). Mental impairment is defined narrowly and means "a diagnosis of post-traumatic stress disorder." Article 2, Section 1,
. It is at least arguable that the injury to Schuette’s back and shoulder was caused by a PTSD nightmare and therefore might be com-pensable under Lockwood, which allows compensation for physical injuries that result from mental stimulus. See Egeland v. City of Minneapolis,
