dispute over sale of car to minor under CA contract law

Contracts: My jurisdiction is: Shasta County, California

Hello,

Here is my legal issue. My brother-in-law (buyer) is 16 years old, lives in California, and only has a divers permit (not even an ID). He purchased a vehicle from a private party (seller). Money was transferred to the seller and buyer drove the car home. The seller partially completed the "Vehicle/vessel Transfer and Reassignment form". The only thing the seller filled out was his name, date, signature, and address. The buyer did not sign anything (we have original copy).

From other postings, I learned that generally, a person under the age of 18 that enters into a contract is voidable.

My mother-in-law does not want the car and we are thinking about taking the matter to civil court to have the seller return the money. We feel he the seller took advantage of the minor in this transaction. I had already spoken to the DMV and they cannot do anything and that I should resolve the matter in civil court. I Do you think the law is on our side? If so, what will we need to prove and what documentations will be important to our case?

Here are some other facts:
1. CALIFORNIA VEHICLE CODE SECTION 15500 states "It is unlawful for any minor who does not possess a valid driver's license issued under this code to order, purchase or lease, attempt to purchase or lease, contract to purchase or lease, accept, or otherwise obtain, any vehicle of a type subject to registration."
2. I asked the seller if he knew if the buyer was underage and he said yes. I asked the seller if he knew that the buyer did not have a valid driver's license. Seller said, "I asked him if he had a driver’s license and he said yes." Then I asked him if he checked for the license to verify. He said, "He looked like a kid who would have one and I didn't think it was necessary to ask." I asked the buyer if this was true. The buyer said the seller never asked. The buyer did mention that he mentioned to the seller that he only had a permit.
3. This probably has nothing to do with the issue. The buyer received original copy of "Certificate of title" from the seller; however, the name on the certificate is prior owner. The certificate has the prior owner’s signature releasing the property and the back has the "application for transfer by new owner" and was completed by the seller. I believe the seller bought the car, fixed it up, then sold it to the buyer and did not register with the DMV or pay the state use tax. Do you think this guy can be in legal trouble with the law if we report this to the authority? If so, who should I contact? Police? district attorney? - Is this your question? Add additional information