Addington v. Texas, 441 U.S. 418 (1979), was a landmark decision of the US Supreme Court that set the standard for involuntary commitment for treatment by raising the burden of proof required to commit persons for psychiatric treatment from the usual civil burden of proof of "preponderance of the evidence" to "clear and convincing evidence".

The court said the issue of an individual's interest in liberty is of such weight and gravity that a higher standard of proof is required than is normal in civil cases brought under state law.

Because of the uncertainties of psychiatric diagnosis, the burden of proof does not need to be as high as "beyond a reasonable doubt" in criminal cases, but should be a "clear and convincing" standard of proof as required by the Fourteenth Amendment in such a civil proceeding to commit an individual involuntarily for an indefinite period to a state psychiatric hospital.

[4] Further, the opinion touched on the issue of an involuntary commitment as primarily medical in nature and needing the expertise of mental health experts.

Whether the individual is mentally ill and dangerous to either himself or others and is in need of confined therapy turns on the meaning of the facts which must be interpreted by expert psychiatrists and psychologists.