Michigan’s constitution defines fetal viability as the point in pregnancy when, in the professional judgment of an attending health care professional and based on the particular facts of the case, there is a significant likelihood of the fetus’s sustained survival outside the uterus without the application of extraordinary medical measures. That definition sits in Article I, Section 28 of the Michigan Constitution, added by voters in November 2022 through Proposal 3, the Reproductive Freedom for All amendment.1City of Saginaw. Proposal 3 Amendment Text in Full No specific gestational week appears anywhere in the text.
What the Constitutional Definition Actually Says
Three features of the language do the real work.
The judgment belongs to the attending health care professional. Not the legislature, not a court, not a hospital board, not a state agency. The clinician caring for the patient makes the call.1City of Saginaw. Proposal 3 Amendment Text in Full
The determination is made on the particular facts of the case. Viability is assessed pregnancy by pregnancy, not applied as a blanket rule to every patient at a given number of weeks.
The standard is a significant likelihood of sustained survival outside the uterus without extraordinary medical measures. Both halves matter. Survival has to be sustained, not momentary, and it has to be achievable without extraordinary intervention.
Why There Is No Fixed Gestational Week
The framers of the amendment left viability as a clinical determination rather than a legislative one because that is how viability actually works in medicine. There is no single test that confirms whether a fetus can survive outside the womb. Providers evaluate a combination of gestational age, estimated fetal weight, genetic factors, availability of neonatal intensive care, and other clinical indicators to estimate the likelihood of survival.
Two pregnancies at the same gestational age can produce very different viability assessments depending on fetal development and clinical circumstances. Medical organizations have long described viability as a probability estimate rather than a binary determination, and the constitutional language reflects that reality rather than imposing a bright-line cutoff medical science does not support.
What Changes at Viability Under Michigan Law
Before viability, the state’s ability to regulate abortion is sharply limited. The amendment protects reproductive freedom as a fundamental right, and any state restriction must serve a compelling interest achieved by the least restrictive means. That compelling interest is defined narrowly: it must be for the limited purpose of protecting the health of the person seeking care, consistent with accepted clinical standards and evidence-based medicine, and it cannot override the patient’s autonomous decision-making.1City of Saginaw. Proposal 3 Amendment Text in Full
After viability, the state can regulate abortion, but with a hard limit. The state can never prohibit an abortion that, in the professional judgment of an attending health care professional, is medically indicated to protect the life or physical or mental health of the pregnant individual.1City of Saginaw. Proposal 3 Amendment Text in Full
The health exception is broader than many people assume. It covers physical health, mental health, and life. The determination rests with the attending health care professional. And the constitutional text does not require the threat to be imminent or the condition to be immediately life-threatening.
Fetal Anomalies and the Health Exception
The amendment does not contain a standalone exception for severe or lethal fetal anomalies independent of the health exception. In practice, clinicians navigating a diagnosis of a serious fetal condition assess whether continuing the pregnancy creates a qualifying health risk for the pregnant person, which often encompasses the physical and psychological toll of carrying a pregnancy with a fatal fetal condition. Post-viability abortion in these circumstances proceeds through the health exception, not a separate anomaly provision.
Attempts to Replace the Clinical Standard with a Gestational Week
Legislation to swap the case-by-case clinical judgment standard for a fixed number of weeks has been introduced but not enacted. House Bill 4108, introduced in the 2023-2024 legislative session, would have defined viability as “the number of gestational weeks, as determined by the American College of Obstetricians and Gynecologists, when there is a significant likelihood of the fetus’s sustained survival outside of the uterus without the application of extraordinary medical measures.”2Michigan Legislature. House Bill No. 4108
Unless legislation of that kind passes and survives constitutional scrutiny, viability in Michigan remains what the attending provider says it is, based on the facts of the pregnancy in front of them.
What This Means for Patients
No Michigan law requires a provider to refuse abortion care at a specific number of weeks. The legal question is always whether the attending health care professional, exercising professional judgment on the particular facts, determines that viability has been reached, and, if so, whether the abortion is medically indicated to protect the patient’s life or physical or mental health.
Because viability is a clinical judgment, patients seeking care later in pregnancy will find that providers reach different conclusions in different cases. A provider may determine that a particular pregnancy has not reached viability even at a gestational age when many others would have. A provider may also determine that viability has been reached but that the health exception applies. Neither outcome is dictated by a chart or a statute; both flow from the clinician’s assessment.
What This Means for Providers
Providers who perform abortions after viability need to be prepared to demonstrate that the procedure was medically indicated to protect the patient’s life or health, because the state retains authority to regulate in that window. Thorough clinical documentation of the viability assessment and, where applicable, the health indication is the strongest safeguard against later challenge.
The constitutional amendment also bars the state from penalizing or prosecuting anyone based on pregnancy outcomes, including miscarriage, stillbirth, or abortion, and shields individuals who help a pregnant person exercise their reproductive rights with voluntary consent.1City of Saginaw. Proposal 3 Amendment Text in Full The Michigan Board of Medicine retains general authority over physician licensing and discipline, including the ability to investigate whether care met accepted medical standards, so the professional-conduct side of practice continues to operate on top of the constitutional floor.
The Short Version
Michigan defines viability by clinical judgment, not by the calendar. The attending health care professional decides, based on the specific pregnancy, whether the fetus has a significant likelihood of sustained survival outside the uterus without extraordinary medical measures. Before viability, the state’s power to regulate abortion is tightly constrained. After viability, the state can regulate, but it cannot prohibit an abortion the attending professional judges medically indicated to protect the patient’s life or physical or mental health. That framework is set by the Michigan Constitution and applies statewide.