My son was 13 years old when he was sentenced to a boys home for a year and now is 25 and is charged with oral copulation with a 16 year old. Can the courts use this against him? It's been 12 years. We live in California.

Why was he sentenced as a boy?

No, this cannot be used against him as he was a minor. Your record essentially is closed once you reach age 18 and you become an adult.