CA Penal Code Section 25220

(a)

The fact that the person who allegedly violated Section 25200 attended a firearm safety training course prior to the purchase of the firearm that is obtained by a child in violation of Section 25200 shall be considered a mitigating factor by a district attorney when deciding whether to prosecute the alleged violation.

(b)

In any action or trial commenced under Section 25200, the fact that the person who allegedly violated Section 25200 attended a firearm safety training course prior to the purchase of the firearm that was obtained by a child in violation of Section 25200 is admissible.