So then the legal system should award status based on usefulness and intelligence, not age as in the present system.

http://en.wikipedia.org/wiki/Emancipation_of_minors

"In most countries of the world, adolescents below the legal age of majority (adulthood) may be emancipated in some manner: through marriage, economic self-sufficiency, educational degree or diploma, military service, or obtaining medical conditions in a form of diseases such as AIDS, HPV, or other STDs."