Legal Question in Civil Rights Law in California

How? With great difficulty and no assurance of success. By defending it with whatever admissible and credible evidence, witnesses, facts, law and legal arguments he may have. By researching and filing appropriate Opposition pleadings, conducting the hearing[s], introducing the evidence, presenting and examining the witnesses, making the legal arguments, etc. If he doesn't know how to do all those things effectively, then hire an attorney that does. He is not going to get a law school education and legal procedures training from a couple free hints and tips to you here. Now that you have the tips you asked for, can he use them? It is a sad fact that most people greatly overestimate their abilities and talents, and think they know how to do 'anything' they want. He'll have a humbling and painful lesson when confronted by the reality in court. And, oh, by the way, imposition of a DV restraining order has an effect similar to a criminal conviction on his 'permanent record'.