Arizona Revised Statutes § 12-542(A)(1) establishes a two-year statute of limitations for medical malpractice claims, measured from when the cause of action accrues. Unlike many jurisdictions, Arizona does not impose a statute of repose, meaning no absolute outer deadline exists from the date of the allegedly negligent act.
This article examines Arizona's statute of limitations framework under A.R.S. § 12-542(A)(1), including discovery rule requirements, tolling exceptions for minors and mental incapacity, procedural requirements affecting medical malpractice claims, and recent judicial developments addressing constitutional limitations on legislative immunity attempts.
Core Rules for Medical Malpractice Statute of Limitations in Arizona
Arizona's medical malpractice limitations framework combines statutory deadlines with judicially developed discovery principles. The following rules govern filing requirements, repose periods, discovery accrual standards, and the distinction between professional negligence and other claim types.
Two-Year Filing Requirement
A.R.S. § 12-542(A)(1) requires medical malpractice actions to commence within two years after the cause of action accrues. The statute explicitly incorporates the definition of medical malpractice found in A.R.S. § 12-561, which encompasses actions against health care providers arising out of the rendering of or failure to render health care services. This two-year period applies uniformly to claims against physicians, hospitals, nurses, and other licensed health care professionals.
Absence of Statute of Repose
Arizona does not impose a statute of repose for medical malpractice claims. Review of A.R.S. § 12-542 and A.R.S. § 12-564 confirms no absolute outer time limit measured from the date of the allegedly negligent medical act. If a medical injury remains genuinely undiscoverable, a claim may theoretically be brought decades after treatment, provided filing occurs within two years of discovery.
Discovery Rule Requirements
The Arizona Supreme Court in Kenyon v. Hammer, 142 Ariz. 69 (1984) established that the limitations period commences when the plaintiff knows or, in the exercise of reasonable diligence, should have known of both elements:
- The fact of injury.
- The negligent cause of that injury.
This conjunctive test requires satisfaction of both prongs before the statute begins running. Constructive knowledge triggers the limitations period even absent actual knowledge.
Scope of Professional Negligence
Medical malpractice under A.R.S. § 12-561(2) encompasses actions against health care providers arising out of the rendering of or failure to render health care services. The definition extends to emergency medical services as defined in A.R.S. § 36-2201, ensuring coverage of professional negligence claims across various healthcare settings.
When the Malpractice Statute Does Not Apply
Arizona's two-year medical malpractice statute applies exclusively to claims "arising out of the rendering of or the failure to render health care services." Claims arising from premises liability, general negligence unrelated to treatment decisions, or intentional torts may be governed by different limitation periods.
Tolling Exceptions That Affect Medical Malpractice Statute of Limitations in Arizona
Arizona recognizes several statutory and common-law tolling doctrines that suspend or delay the running of the medical malpractice limitations period. The following tolling categories apply under Arizona law.
1. Minority Tolling
A.R.S. § 12-502 provides general minority tolling that suspends the statute of limitations during the entire period of minority for individuals under age 18 at the time the cause of action accrues. Under this general provision, minors have until their twentieth birthday to file personal injury claims.
However, for medical malpractice claims specifically, A.R.S. § 12-564(D) historically created a more limited protection for children injured before their seventh birthday, capping tolling at the child's tenth birthday. The Arizona Supreme Court in Barrio v. San Manuel Div. Hosp., 143 Ariz. 101 (1984) struck down this restriction as unconstitutional under the anti-abrogation clause, reasoning that a statute barring claims before a child can legally act on their own behalf effectively eliminates the right to recovery. Following Barrio, minors injured by medical malpractice are entitled to the full minority tolling period under A.R.S. § 12-502.
2. Mental Incapacity Tolling
A.R.S. § 12-502 provides tolling for persons of unsound mind, continuing until removal of the disability. Mental incapacity must exist at the time the cause of action accrues—incapacity arising after accrual does not toll the limitations period.
Courts require evidence demonstrating the plaintiff lacked the mental capacity to understand legal rights or manage personal affairs. Physical infirmity alone is insufficient, and temporary conditions such as medication effects or grief do not qualify. The burden falls on the plaintiff to establish incapacity through medical documentation or other competent evidence.
3. Fraudulent Concealment
Arizona recognizes fraudulent concealment as a common-law tolling doctrine. The Arizona Supreme Court in Walk v. Ring, 202 Ariz. 310 (2002) established three essential elements:
- Affirmative acts of concealment.
- Fraudulent conduct.
- Prevention of discovery despite reasonable diligence.
4. Foreign Object Discovery
Arizona does not maintain a separate statutory provision for foreign object cases. Such cases are governed by the general discovery rule framework, requiring plaintiffs to file within two years of discovering or reasonably should have discovered the injury.
How Arizona Courts Interpret Medical Malpractice Statute of Limitations Rules
Arizona courts have developed the state's medical malpractice limitations framework through significant appellate decisions addressing discovery, tolling, and constitutional limitations on legislative modifications. The following cases clarify ambiguous statutory language and establish precedent for deadline calculation.
Kenyon v. Hammer — Discovery Rule Framework
The Arizona Supreme Court in Kenyon v. Hammer, 142 Ariz. 69, 688 P.2d 455 (1984) established the foundational discovery rule framework. The court held that the statute commences when the plaintiff knows or should have known both the fact of injury and its negligent cause, with inquiry notice—sufficient facts to prompt investigation—triggering the limitations period.
The case arose when a nurse incorrectly recorded a pregnant patient's blood type as Rh-positive rather than Rh-negative, leading to the stillbirth of the couple's second child and personal injuries to the mother. The plaintiffs filed suit within two years of the stillbirth but more than three years after the negligent blood typing occurred. The court rejected the argument that the statute ran from the date of the negligent act, holding that the limitations period could not begin until the plaintiffs had reason to connect their loss to medical negligence.
Roebuck v. Mayo Clinic — Constitutional Limitations on Immunity Statutes
The Arizona Supreme Court in Roebuck v. Mayo Clinic, No. CV-23-0262-PR (2025) held that A.R.S. § 12-516(A), which attempted to limit health care provider liability during the COVID-19 public health emergency, violates Article 2, Section 31 of the Arizona Constitution's anti-abrogation clause. This establishes that constitutional protections prevent legislative attempts to eliminate traditional medical malpractice claims through immunity statutes.
The case arose when Robin Roebuck, a heart and kidney transplant recipient, was hospitalized at Mayo Clinic in April 2020 with COVID-19 symptoms. Physicians ordered an arterial blood gas test that resulted in complications requiring surgery on his right hand, forearm, and wrist, leaving him with diminished strength and significant scarring. When Roebuck filed an ordinary negligence claim, Mayo Clinic invoked the statute requiring proof of gross negligence for COVID-related care—the court held that completely eliminating ordinary negligence claims violated constitutional protections.
Walk v. Ring — Fraudulent Concealment and Discovery Standards
The Arizona Supreme Court in Walk v. Ring, 202 Ariz. 310, 44 P.3d 990 (2002) reversed dismissal of a dental malpractice claim filed more than two years after treatment, holding that the discovery rule delayed accrual until the plaintiff had sufficient information to suggest investigation was warranted. The court established that a defendant's assurances of proper care can prevent inquiry notice even when symptoms appear immediately.
The case arose when a patient experienced severe temporomandibular joint pain immediately after dental reconstruction work, but was assured by the dentist that the treatment was performed properly. Five years later, a subsequent dentist indicated the original work may have been substandard. The court held that until the second dentist's opinion, the patient lacked sufficient facts to trigger a duty to investigate—the original dentist's assurances reasonably explained the ongoing symptoms without suggesting negligence.
Recent Updates to Medical Malpractice Statute of Limitations Laws in Arizona
Arizona has not enacted legislative amendments to its medical malpractice statute of limitations between 2023 and 2026. House Bill 2157, introduced in the 2024 legislative session, proposed extending the limitations period from two years to five years and codifying the discovery rule established in Kenyon v. Hammer. The bill passed both chambers but was vetoed by Governor Katie Hobbs on April 8, 2024, citing concerns about increased litigation costs and potential impacts on malpractice insurance premiums.
The most significant judicial development was the Arizona Supreme Court's September 12, 2025 decision in Roebuck v. Mayo Clinic, invalidating A.R.S. § 12-516(A)'s heightened standard for COVID-19-era medical malpractice claims. The ruling allows patients who filed claims during the pandemic period to proceed under ordinary negligence standards rather than the gross negligence threshold the legislature imposed. Plaintiffs whose claims were previously dismissed under the now-void statute may seek to revive those actions, though those who never filed may be barred by the standard two-year limitations period.
What This Means for Medical Malpractice Filing Deadlines in Arizona
Arizona's two-year limitations period under A.R.S. § 12-542(A)(1) commences when the plaintiff knows or should have known of both the injury and its negligent cause. The absence of a statute of repose places particular emphasis on discovery and reasonable diligence standards. The 60-day notice requirement under A.R.S. § 12-575 tolls the statute until 75 days after the healthcare provider receives notice.
Accurate medical records and documented treatment timelines establish discovery dates under Arizona's discovery rule framework. Legal technology supports comprehensive case preparation by organizing records, building defensible chronologies, and tracking statutory deadlines tied to case facts.
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