How to Determine Competency in Legal and Medical Matters

Determining competency in legal and medical matters comes down to who is asking and what decision is at stake: a judge decides legal competency after weighing expert evaluations, while a treating physician decides medical decision-making capacity at the bedside. Both start from the same presumption — every adult is competent until specific evidence shows otherwise — and both look at the particular decision in front of the person, not at a diagnosis or a general impression of mental health.

Who Decides, and Under What Standard

Legal competency is a judicial finding. A court hears evidence, usually including a report from a licensed psychiatrist or psychologist, and issues a ruling that carries legal consequences. Medical decision-making capacity is a clinical judgment made by the treating physician; any licensed physician can perform the assessment, and a psychiatrist is consulted only in complex cases.¹

The standard itself shifts with the decision. The competency required to stand trial in a felony case is higher than the capacity needed to sign a will, and the capacity to consent to a routine blood draw is lower still. A person can meet one standard and fail another on the same day.

Competency to Stand Trial

The federal standard traces to the Supreme Court’s 1960 decision in Dusky v. United States. A defendant must have a sufficient present ability to consult with their lawyer with a reasonable degree of rational understanding, and a rational and factual understanding of the proceedings.² Mental illness by itself is not the question. The question is whether the defendant can meaningfully participate in their own defense right now.

Under 18 U.S.C. § 4241, the defendant, the prosecutor, or the court itself can raise competency at any point between the start of a criminal case and sentencing. The threshold for ordering a hearing is “reasonable cause to believe” the defendant may have a mental disease or defect that prevents them from understanding the proceedings or assisting counsel.³ Most states use a nearly identical standard.

If the court orders an evaluation, the examiner’s report must include the person’s history, current symptoms, the tests used, and an opinion on whether the defendant can understand the proceedings and assist in their defense.⁴ The judge weighs that report and rules. No evaluator can declare someone incompetent on their own.

Common triggers include difficulty communicating with counsel, apparent confusion about the charges, disorganized or delusional thinking in court, or a known history of severe mental illness.

Civil Competency for Wills and Contracts

Civil competency questions come up most often around wills and contracts, and the thresholds are lower than the standard for standing trial.

To make a valid will, a person needs testamentary capacity: they must understand that they are making a will, what property they own, who their natural heirs are, and how those elements fit into a plan for distributing the estate. Most states also require the person to be at least 18. Someone with mild cognitive impairment can still have testamentary capacity if they meet these criteria during a lucid interval.

For contracts, the standard in most states is whether the person understood the meaning and effect of the agreement when they signed it. A contract signed by someone who lacked capacity is generally voidable — the incapacitated person or their legal representative can cancel it, but the other party cannot. Contracts for necessities like food, housing, and medical care are an exception and may be enforced anyway.

Medical Decision-Making Capacity

A physician assessing capacity is looking at four abilities in relation to a specific medical decision:

The patient can understand the relevant medical information, including risks, benefits, and alternatives.
The patient appreciates how that information applies to their own situation.
The patient can reason through the options, weighing tradeoffs and consequences.
The patient can express a clear and consistent choice.¹

Capacity is decision-specific and can fluctuate. A patient with dementia might have capacity to consent to a blood draw but lack capacity to decide about surgery. Someone confused after sedation in the morning may regain full capacity by afternoon. A diagnosis alone never settles the question; the assessment has to focus on what the patient can actually demonstrate at the time the decision needs to be made.

Typical triggers for a capacity assessment include a sudden change in mental status, a patient refusing a strongly recommended lifesaving treatment, a new psychiatric diagnosis, or a sense from the team that the patient does not really understand what they are agreeing to. The treating physician starts the assessment. Family members can raise concerns, but they cannot unilaterally declare a patient incapable.

How the Evaluation Is Conducted

Whether the question is legal or medical, a competency or capacity evaluation follows a similar structure.

Direct Interview and Mental Status Exam

The evaluator interviews the person, assessing orientation, memory, thought process, and understanding of the specific situation. In a criminal competency evaluation, that means testing whether the defendant can describe the charges, identify courtroom roles, and explain how they would work with their attorney. For medical capacity, it means asking the patient to explain their diagnosis, the proposed treatment, and the risks of refusing. The evaluator is looking for functional understanding, not the ability to recite facts.

Standardized Testing

Evaluators often use structured instruments. For medical capacity, the MacArthur Competence Assessment Tool for Treatment (MacCAT-T) rates understanding, reasoning, appreciation, and expression of a choice.⁵ Legal competency evaluations may include neuropsychological batteries measuring memory, attention, executive function, and reasoning. Scores at the extremes carry the most weight; middle-range scores require clinical judgment.¹

Collateral Information

No evaluation should rest solely on the interview. Evaluators review medical records, legal documents, and treatment histories, and they speak with family members, caregivers, and others who see the person regularly. This context helps distinguish a typical presentation from an unusually good or bad day. In court-ordered cases, the report must document the tests used, the findings, and the clinical opinion.⁴

Rights of the Person Being Evaluated

A person whose competency is being questioned keeps their rights during the process. In federal criminal proceedings, the defendant is entitled to counsel, to testify, to present evidence, to call witnesses, and to cross-examine the witnesses at the hearing.⁶ Most states provide equivalent protections in criminal and civil competency proceedings.

In guardianship cases, the person (often called the respondent) generally has a right to notice, a right to attend the hearing, a right to counsel, and a right to present their own evidence of capacity. Some states appoint an independent attorney or guardian ad litem if the respondent has none.

Courts must also provide reasonable accommodations under Title II of the Americans with Disabilities Act.⁷ For someone with a cognitive or communication disability, that can mean assistive listening devices, qualified interpreters, large-print materials, or adjusted courtroom lighting. The court is not required to provide accommodations that would fundamentally alter the proceeding, but it must give primary consideration to what the person requests.

The presumption of competency itself is a legal protection. A statutory presumption of competency does not violate due process; the party challenging competency carries the initial burden.⁸

What Happens After an Incompetency Finding

The consequences depend on the setting, but all of them involve some loss of decision-making authority.

A criminal defendant found incompetent to stand trial cannot be prosecuted until competency is restored. The court typically orders inpatient or outpatient treatment for a set period, followed by another evaluation. If competency is restored, the case moves forward. Federal law limits how long a person can be held for restoration and requires periodic review.³

In civil matters, a finding of incapacity can lead to appointment of a guardian (personal and healthcare decisions) or a conservator (finances and property). States use different terminology, but the split between personal authority and financial authority is standard. The person under guardianship loses the corresponding rights, which can include where to live, what medical care to accept, and how to spend money.

Courts can also issue limited guardianships or conservatorships covering only the specific areas where the person lacks capacity. Less restrictive options, such as supported decision-making agreements, representative payees for Social Security benefits, or trusts managed by a trustee, can meet the need without a full guardianship. Courts are increasingly required to consider these before appointing a guardian.⁹

Restoring Capacity

An incompetency finding is not necessarily permanent. If a person’s condition improves through treatment, medication, recovery, or time, they can petition the court to restore their rights. The person seeking restoration carries the burden of proving the need for guardianship has ended. Courts rely mainly on a fresh medical or psychological evaluation showing improved capacity and the judge’s own observation of the person in court. Testimony from family and caregivers helps but is usually treated as secondary to the clinical evaluation.

For criminal defendants, restoration follows the treatment-and-re-evaluation track. Federal law generally does not allow holding someone for restoration longer than it would take to determine whether there is a substantial probability they will regain competency in the foreseeable future.³

Planning Ahead So You Keep Control

The most reliable way to keep decision-making authority over your own life if you later lose capacity is to sign the right documents while you are still competent. Wait until a crisis, and someone else — possibly a court-appointed stranger — will decide for you.

An advance directive gives instructions for medical care and only takes effect if you cannot communicate your own wishes.¹⁰ The two main forms are a living will, which specifies which treatments you want under specific circumstances, and a durable power of attorney for healthcare, which names someone (a healthcare proxy) to make medical decisions when you cannot. Most estate planning attorneys recommend having both.

A durable power of attorney for finances covers money and property and stays valid after you become incapacitated. Some people use a “springing” power of attorney that activates only when a physician certifies in writing that the person has lost capacity. Banks and financial institutions sometimes refuse to honor springing powers of attorney without heavy documentation or a court order, so an immediately effective durable power of attorney with a trusted agent is usually simpler in practice.

Without an advance directive, state law decides who speaks for you — typically a spouse, then parents, then adult children. Unmarried partners who have not been formally named may be shut out entirely.¹⁰

1
American Academy of Family Physicians. Evaluating Medical Decision-Making Capacity in Practice
2
Justia. Dusky v. United States, 362 U.S. 402 (1960)
3
Office of the Law Revision Counsel. 18 U.S. Code 4241 – Determination of Mental Competency to Stand Trial
4
Office of the Law Revision Counsel. 18 U.S. Code 4247 – General Provisions for Chapter
5
National Library of Medicine. The MacCAT-T: A Clinical Tool to Assess Patients Capacities to Make Treatment Decisions
6
United States Department of Justice. Criminal Resource Manual – 63. Standards For Determining Competency And For Conducting A Hearing
7
Office of the Law Revision Counsel. 42 USC 12132
8
Legal Information Institute. U.S. Constitution Annotated – Competency for Trial
9
Elder Justice Initiative. Guardianship: Less Restrictive Options
10
National Institute on Aging. Advance Care Planning: Advance Directives for Health Care