Who has the ultimate authority to determine an inpatient's capacity to consent when both the attending inpatient medicine physician and a consulting psychiatrist are involved?

Who Makes the Final Decision on Capacity to Consent?

The treating physician (in this case, the inpatient medicine physician) makes the final determination of capacity to consent, not the consulting psychiatrist. 1

Legal Framework for Capacity Determination

The responsibility for assessing capacity lies with the physician who is treating the patient or performing the proposed procedure. 1 This is a fundamental principle across medical-legal frameworks:

• The treating physician must personally satisfy themselves that the patient has (or lacks) capacity before proceeding with any intervention. 1
• Capacity assessment is decision-specific and must be evaluated anew for each therapeutic decision by the treating physician. 1
• The assessment must be documented in the medical record along with details of the information provided to the patient. 1

The Psychiatrist's Role is Consultative Only

When doubt exists about a patient's capacity, a psychiatric consultation may help determine whether the patient can make a sound judgment. 1 However, this is explicitly framed as assistance, not transfer of authority:

• Psychiatric consultation provides expert input but does not remove the treating physician's responsibility for the final capacity determination. 2, 3
• The psychiatrist evaluates cognitive and psychiatric factors that may impair decision-making capacity but does not assume decision-making authority for medical treatments. 3, 4
• Research demonstrates that multidisciplinary assessment (involving residents, chief residents, and nurses) shows the best agreement with psychiatric evaluation (sensitivity 78.6%, specificity 94.3%), suggesting collaborative assessment is ideal but ultimate authority remains with the treating team. 2

Practical Algorithm for Capacity Determination

Step 1: Initial Assessment by Treating Physician

• The inpatient medicine physician assesses whether the patient can understand, retain, use and weigh relevant information, and communicate their decision. 1
• Assumptions about capacity cannot be based on age, appearance, behavior, or specific conditions like learning disabilities. 1

Step 2: When Uncertainty Exists

• Request psychiatric consultation to evaluate cognitive, psychiatric, or neurological factors affecting capacity. 1, 3
• The psychiatrist provides expert opinion on mental status and decision-making abilities. 4

Step 3: Final Determination

• The treating physician integrates the psychiatric consultation with their own clinical assessment and makes the final capacity determination. 1, 2
• If the patient is referred by another clinician who knows the patient better, a multidisciplinary discussion and joint decision is recommended, with documentation in clinical notes. 1

Critical Pitfalls to Avoid

Do not assume the psychiatrist's opinion is binding. Clinical impressions alone (including psychiatric assessments) can be inaccurate—one study found that while standardized tools had poor sensitivity (35.7%), even experienced clinicians' assessments were imperfect. 5, 2 The treating physician must independently verify capacity.

Do not confuse capacity with competency. Capacity is a clinical determination made by physicians; competency is a legal determination made by courts. 3 The treating physician determines capacity, not legal competency.

Do not delay necessary treatment waiting for psychiatric consultation unless the delay would not cause additional harm. 1 In urgent situations where capacity is uncertain, the treating physician must make decisions based on the patient's best interests and document the circumstances. 1

When There is Disagreement

If the treating physician and consulting psychiatrist disagree about capacity:

• The treating physician's determination prevails as they hold legal responsibility for the patient's care. 1
• Seek legal advice when significant uncertainty or disagreement exists, particularly for high-stakes decisions. 1
• Consider involving the Court of Protection (in UK jurisdictions) or seeking court-appointed guardianship (in US jurisdictions) when disputes cannot be resolved. 1, 6