¶ 1 Article 18, Section 8 of the Arizona Constitution mandates that an employee receive workers’ compensation if the employee is injured in “any accident arising out of and in the course of ... employment,” and the injury “is caused in whole, or in part, or is contributed to, by a necessary risk or danger of such employment, or a necessary risk or danger inherent in the nature thereof, or by failure of such employer or its agents or employee or employees to exercise due care.” The issue in these consolidated matters 1 requires us to determine whether Article 18, Section 8 precludes the legislature from requiring proof that the presence of alcohol or illegal drugs in an injured worker’s system was not a contributing cause of the accident before workers’ compensation benefits may be awarded.
I
A
¶2 David C. Grammatieo, who installed metal trim on building exteriors for AROK, Inc., performed his work on drywall stilts approximately forty-two inches in height. After working for most of his shift on stilts, Grammatieo fell while walking, on stilts, through a cluttered area of the job site. He broke his right wrist and left knee in the fall.
¶ 3 Grammatieo admitted that he had smoked marijuana and ingested methamphetamine on the previous two days, days he was not required to be at work. His post-accident urine test showed positive results
¶ 4 After the hearing, the administrative law judge found Grammatico’s claim noncom-pensable because Grammatico failed to prove that his use of unlawful controlled substances “was not even a ‘slight contributing cause’ ” of his injuries. Grammatico then filed a statutory special action in the court of appeals.
See
A.R.S. § 23-95RA) (1995). The court of appeals set aside the judge’s award, holding that A.R.S. § 23-1021(D) violates Article 18, Section 8 of the Arizona Constitution.
Grammatico v. Indus. Comm’n,
B
¶ 5 Austin Komalestewa worked for Stone-ville Pedigree Seed. Shortly after he began work one morning, Komalestewa, as he and his fellow workers often were required to do, tried to fix a conveyor belt that had “bogged down.” He crawled under the belt to put pressure on the drum, and his arm became caught in the belt, resulting in serious injury. Komalestewa’s employer’s insurance carrier denied his workers’ compensation claim because blood tests taken at the hospital shortly after the accident revealed alcohol in his blood. Komalestwa protested the denial of benefits, and hearings were conducted before an administrative law judge at the Industrial Commission.
¶ 6 During the hearing, Komalestwa admitted that he had four mixed drinks containing vodka the night before the accident. An expert testified that based on blood drawn after the accident, Komalestewa’s blood-alcohol level at the time of the accident would have been at least 0.176 percent. However, Komalestewa’s wife, the employer’s site manager, and a co-worker testified that Komales-tewa did not appear intoxicated the morning of the accident.
¶ 7 The administrative law judge initially determined that Komalestewa had sustained a compensable injury. Subsequently, however, upon request for review by the insurance carrier, see A .R.S. §§ 23-942(D), -943(A)-(B) (1995), the judge determined that the claim was noncompensable under AR.S. § 23-1021(C) because Komalestewa’s intoxication had contributed to the accident. That section provides that “[a]n employee’s injury ... shall not be considered a personal injury by accident arising out of and in the course of employment and is not compensable ... if the impairment of the employee is due to the employee’s use of alcohol ... and is a substantial contributing cause of the employee’s personal injury.” Id. “‘Substantial contributing cause’ means anything more than a slight contributing cause.” Id. § 23-1021(H)(2).
¶ 8 Komalestewa filed a statutory special action in the court of appeals. In affirming the award, another panel of that court rejected the majority’s approach in
Grammatico
and held that A.R .S. § 23-1021(C) did not violate Article 18, Section 8 of the Arizona Constitution.
Komalestewa v. Indus. Comm’n,
C
¶ 9 In
Grammatico,
Arok and the State Compensation Fund petitioned the Court for review, and Komalestewa petitioned for review in his matter. We granted review in both cases because of the conflict between the panels of the court of appeals on the applicability of Article 18, Section 8 and be
II
¶ 10 Before statehood, all Arizona employees injured by their employers’ negligence could bring common law tort actions against them.
See Consol. Arizona Smelting Co. v. Ujack,
¶ 11 “For twenty-five years, labor interests had unsuccessfully lobbied for an employer’s liability act in the territorial legislature.” Gordon M. Bakken,
The Arizona Constitutional Convention of 1910,
1978 Ariz. St. L.J. 1,18. Responding to those calls, the framers of the Arizona Constitution in 1910 enacted Article 18, which included a wide range of measures to protect labor.
See id.
at 18-20. Article 18 abolished the fellow servant doctrine and substantially curtailed the defenses of contributory negligence and assumption of risk.
See
Ariz. Const, art. 18, §§ 4, 5;
Heimke v. Munoz,
¶ 12 Although Article 18, Sections 4 and 5 restricted employers’ common law defenses to employee negligence actions, neither section affected the basic requirement that the employee prove negligence and causation, an often long and expensive process for both employees and employers. See Davis, §§ 1.1, at 1-1 & 1.3.1, at 1-6. To address this issue, Delegate Everett E. Ellinwood, “an attorney who had served the railroads and the Phelps Dodge Arizona interests,” John D. Leshy, The Making of the Arizona Constitution, 20 Ariz. St. L.J. 1, 35 (1988), introduced Proposition 72 at the constitutional convention, which proposed to require the legislature to enact a “compulsory workmen’s compensation law.” The Records of the Arizona Constitutional Convention of 1910, 65-66 (John S. Goff ed., 1991) (hereinafter “Goff’). Proposition 72 was approved and adopted by the convention delegates as Article 18, Section 8. 2 Id. at 549, 555, and 886.
¶ 13 After Arizona became a state in 1912, the first session of the Arizona Legislature implemented the constitutional mandate by adopting a “Compulsory Compensation Law.”
Ujack,
¶ 14 Article 18, Section 8 and the implementing statutes provide workers in Arizona with an alternative to common law tort actions against employers. Under this “new civil action,”
Ujack,
¶ 15 This Court recognized that the new civil action was simply an alternative to the still-existing common law tort action. In
In
¶ 16 In 1925, the voters amended Article 18, Section 8
3
to provide for pre-injury election, thus creating a constitutional exception to Article 18, Section 6, the anti-abrogation clause.
Kilpatrick v. Superior Court,
¶ 17 Under the Arizona Constitution, therefore, absent an employee’s express rejection of workers’ compensation, a no-fault system has replaced the prior fault-based tort system.
See Stoecker v. Brush Wellman, Inc.,
Ill
¶ 18 We now turn to whether A.R.S. § 23-1021(D) and A.R.S. § 23-1021(0 violate Article 18, Section 8, as Grammatico and Komalestewa contend. We begin our analysis with a brief summary of a few principles underlying workers’ compensation law.
A
¶ 19 To receive workers’ compensation benefits, an injured employee must demonstrate both legal and medical causation.
DeSchaaf v. Indus. Comm’n,
¶ 20 Medical causation, in contrast, is established by showing that the accident caused the injury.
See id.
By its plain terms, Article 18, Section 8 does not limit the legislature’s power to enact legislation affecting medical causation.
Cf. Ford v. Indus. Comm’n,
¶ 21 Consequently, the legislature has some latitude to establish the requisite medical causation for workers’ compensation recovery. In contrast, however, the legislature may not define legal causation in a way that conflicts with Article 18, Section 8 because the legislature “cannot enact laws which will supersede constitutional provisions adopted by the people.”
Kilpatrick,
B
¶ 22 The resolution of this case, therefore, hinges upon whether A.R.S. § 23-1021(C) and (D) impermissibly define legal causation by requiring proof that the presence of alcohol or illegal drugs in a claimant’s system did not contribute to the industrial accident. Turning first to A.R.S. § 23-1021(D)-(D)(l), those subsections provide that an employee who fails to pass, refuses to cooperate with, or refuses to take a qualified alcohol or drug test, is prohibited from receiving compensation, even if his or her injury would otherwise require compensation, unless the employee can prove that the intoxication or unlawful drug use was not a contributing cause of the accident.
¶ 23 The majority in
Grammatico
concluded that A.R.S. § 23-1021(D) impermissibly restricts legal causation.
C
¶24 Section 23-1021(C), the statute at issue in Komalestewa, similarly runs afoul of Article 18, Section 8. That statute provides that
[a]n employee’s injury or death shall not be considered a personal injury by accident arising out of and in the course of employment and is not compensable pursuant to this chapter if the impairment of the employee is due to the employee’s use of alcohol ... and is a substantial contributing cause of the employee’s personal injury or death. This subsection does not apply if the employer had actual knowledge of and permitted, or condoned, the employee’s use of alcohol____
Id. (footnote omitted).
¶25 Although Article 18, Section 8 requires compensation if a necessary risk or danger of employment partially caused or contributed to the accident, section 23-1021(C) denies benefits if alcohol or drug use contributed to the accident. Thus, even if an accident was caused, in part, by a necessary risk or danger of employment, A.R.S. § 23-1021(C) would preclude benefits if alcohol was “anything more than a slight contributing cause” of the injury. A.R.S. § 23-1021(H)(2). Again, such a provision requires proof that an employee was not at fault when the industrial accident occurred. Article 18, Section 8 does not permit the legislature to enact such a statute.
See Inscoe v. DeRose Indus., Inc.,
IV
A
¶ 26 The dissent in
Grammatico,
as well as the court in
Komalestewa,
concluded that the legislature is permitted to define the phrase in Article 18, Section 8, “a necessary risk or danger of ... employment,” to exclude accidents occurring when the employee has recently used illegal drugs or alcohol before the injury.
See Grammatico,
B
¶27 The dissent in
Grammatico
further concluded that an employee’s drug use before coming to work and suffering an injury is analogous to a meat cutter intentionally cutting off his own hand.
See
¶ 28 To be sure, our courts have long held that employees who intentionally injure themselves may not recover workers’ compensation.
See, e.g., L.B. Price Mercantile Co. v. Indus. Comm’n,
¶ 29 Intentionally self-inflicted injuries, however, bar compensation only to those employees who clearly have purposely inflicted their injuries. In
L.B. Price Mercantile,
for example, we concluded that an employee who violated criminal laws and was injured in the process was not barred from workers’ compensation because such a violation merely established contributory negligence, which does not bar recovery under the workers’ compensation scheme.
¶ 30 But in
Glodo,
the court of appeals determined that the employee had intentionally injured himself by punching a freezer door.
¶ 31 In contrast,
Rural Metro
concluded that an employee’s decision to reject medical advice, which resulted in a workplace injury, did not constitute an intentional injury. There, the employee had suffered a shoulder injury, which required surgery, and was told by her doctor not to return to work.
¶ 32 In distinguishing
Glodo,
the
Rural Metro
court emphasized that the employee in
Glodo
injured himself through an “intentional act of violence.”
Id.
at 135, ¶ 9,
C
¶ 33 Alcohol and drug use is more akin to the facts of
Rural Metro
than to the facts of
Glodo.
While alcohol consumption and illegal drug use shortly before work or during work undeniably increase the chances of being injured on the job, it cannot be unequivocally said that employees with alcohol or drugs in their systems who sustain injuries have
intentionally
injured themselves.
See L.B. Price Mercantile,
Y
¶ 34 We recognize that compelling policy reasons support banning drug and alcohol
we cannot ignore that our constitutional system for workers’ compensation requires the payment of benefits if a necessary risk or danger of employment partially caused or contributed to an industrial accident, without consideration of any fault by the injured employee. Thus, unless and until the constitution is changed, the legislature cannot abrogate claims for workers’ compensation for injuries wholly or partially caused or contributed to by necessary employment risks or dangers solely because an employee fails to pass ... a drug or alcohol test.
¶ 35 Consequently, because the necessary risks and dangers of working on drywall stilts could have partially caused or contributed to Grammatico’s injury, A.R.S. § 23-1021(D) is unconstitutional as applied to deny Grammatico workers’ compensation benefits. Likewise, because the necessary risks and dangers of putting pressure on a drum to fix a “bogged down” conveyor belt could have partially caused or contributed to Komaleste-wa’s injury, A.R.S. § 23-1021(0) is unconstitutional as applied to deny Komalestwa benefits.
VI
¶ 36 For the foregoing reasons, we affirm the court of appeals’ decision in Grammatico setting aside the award, and reverse the court of appeals’ decision in Komalestewa, and set aside the award.
Notes
. By separate order, we consolidated these cases for the purposes of this opinion.
. As originally enacted, Article 18, Section 8 directed the legislature to
enact a Workmen’s Compulsory Compensation law applicable to workmen engaged in manual or mechanical labor in such employments as the Legislature may determine to be especially dangerous, by which compulsory compensation shall be required to be paid to any such workman by his employer, if in the course of such employment personal injury to any such workman from any accident arising out of, and in the course of, such employment is caused in whole, or in part, or is contributed to, by a necessary risk or danger of such employment, or a necessary risk, or danger inherent in the nature thereof, or by failure of such employer, or any of his or its officers, agents, or employee, or employees, to exercise due care, or to comply with any laws affecting such employment; Provided, that it shall be optional with said employee to settle for such compensation, or retain the right to sue said employer as provided by this Constitution.
Goff at 1435-36.
. The amended version of Article 18, Section 8 provided that employees "engaged in ... private employment, may exercise the option to settle for compensation by failing to reject the provisions of such Workmen's Compensation Law prior to the injury.”
. The current version of Larson also discusses this principle. See 2 Arthur Larson & Lex K. Larson, Larson's Workers’ Compensation Law § 46.03[1], at 46-6 (2004).
. The Amicus Curiae Brief of Southern Arizona Workers’ Compensation Claimants Association ("SAWCCA”) points out that Article 18, Section 6, the anti-abrogation clause of Arizona’s constitution, preserves each person's "right of action to recover damages" for injuries. From this, SAWCCA reasons that if an Arizona worker is deprived of the right to worker’s compensation by a statute that introduces fault into the worker's compensation system, the worker retains the remedy of bringing a common law tort action against the employer. Given our disposition of the issues in this consolidated matter, we need not consider SAWCCA's argument.
. Studies demonstrate that talking on cell phones while driving is extremely dangerous. See, e.g., Donald A. Redelmeir & Robert J. Tibshirani, Association Between Cellular-Telephone Calls and Motor Vehicle Collisions, 336 New England Journal of Medicine 453, 456 (1997) (risk of accident increased 400% for drivers using cell phones; “relative risk is similar to the hazard associated with driving with a blood alcohol level at the legal limit”); David L. Strayer et al., Fatal Distraction? A Comparison of the Cell-Phone Driver and the Drunk Driver, http:// www.psych.utah.edu/Ap pli edCognitionLab /DrivingAssessm ent2003.pdf ("cell-phone drivers may actually exhibit greater impairments ... than legally intoxicated drivers”).
. Using over-the-counter cold medicine, such as Benadryl, can significantly increase the chance of automobile accidents. See, e.g., John M. Weiler et al., Effects of Fexofenadine, Diphenhydra-mine, and Alcohol on Driving Performance, 132 Annals of Internal Medicine 354, 362 (2000) (driving performance was generally worse after taking Benadryl than after drinking alcohol).
. L.B. Price Mercantile
did not refer to Article 18, Section 8, but to sections 1421 and 1426 of the Revised Code of 1928.
. The court in
Komalestewa
also used a flawed analogy to argue that an employee who is impaired from either drugs or alcohol has abandoned his or her employment. According to
Komalestewa,
Grammatico's fall while under the influence of drugs is analogous to an employee who, in a moment of tomfoolery, walks across the room on stilts while blindfolded, simply to show his fellow employees that he could, and falls in the process.
See Komalestewa,
209 Ariz.
at 218, ¶ 27,
. In the 2005 session of the legislature, Representative Eddie Farnsworth introduced House Concurrent Resolution 2007, which would have amended Article 18, Section 8 by including language that would have precluded an injured worker from receiving compensation "if an accident [was] caused in whole or in part by a worker's use of alcohol or a controlled substance.” The resolution passed both the Commerce and Judiciary Committees of the House of Representatives but apparently no further action was taken on it. See Minutes of Committee on Commerce, Arizona House, 47th Legislature, 1st Reg. Sess., 7-8 (Feb. 16, 2005), available at http://www.azleg .state.az.us.legalte xt/471eg/lr/ comm — min/house/ 216comm.doc.htm; Minutes of Arizona House Committee on Judiciary, 47th Legislature, 16-17 (Feb. 24, 2005), available at http://www.azleg .state.az.us/legtext /471eg/lr/ comm — min/house /0224jud.doc.htm.
