Expressed consent is when a patient clearly expresses his consent to undertake diagnostic or therapeutic treatment. This may be either verbally expressed or may be expressed in writing after the patient is informed about all the aspects of the diagnostic and therapeutic procedure.

When the patient expresses consent to a specific diagnostic or therapeutic procedure verbally, it is termed as oral or verbal expressed consent. When the consent is given in writing, it is called as written expressed consent. Both these forms of expressed consent are acceptable in the court of law as proof of consent; however, written expressed consent is more valuable as it is a permanent written record. To be legally acceptable, expressed consent must agree to the doctrine of informed consent.