5150 fundamentally means a police code. It is used to mark a situation for bizarre individuals on the loose who can cause trouble of some sort. California Police applies this term for a mentally troubled individual.
The code 5150 stands for someone in the state of California who is thought by officers to be mentally unstable and a danger. Code 5150 allows officers to hold the person for psychiatric evaluation.
5150 is a section of the California Welfare and Institutions Code. It is an involuntary psychiatric hold that can be administered by a qualified officer or clinical if a person is a danger to themselves.