(Photo credit: Stephen Lovekin/Getty Images)

Actor Jason Patric appeared before California's Assembly Judiciary Committee today to lobby for a bill that would allow him to seek paternity rights for his 3-year-old son, Gus.

The "Lost Boys" actor and his ex-girlfriend, Danielle Schreiber, conceived Gus via in vitro fertilization. Since their split, they have disagreed over the role Patric, 48, was to play in the boy's life, and the law defines him as merely a sperm donor.

This bill would allow sperm donors to petition for rights to a child if they can prove a certain level of intended involvement.

"I have to be Gus' voice - my son - a voice that I have not heard in 25 weeks, a voice that is not allowed to mention my name in his mother's home, a voice that has sent me here to speak to you all," Patric said.

He added that he was also speaking out on behalf of other men in his situation.

"We raised these children, we loved these children, but when these relationships fell apart we were shockingly hit with briefs that deemed us 'sperm donors': a word that was never, ever mentioned in my house, a word I can guarantee you Gus doesn't know how to pronounce," Patric said.

Jason Patric Advocates For Sperm Donors' Rights

Patric argued that a "a loophole" in the law gives his child's mother the right to keep him from their child because Gus was conceived with artificial reproduction technology and because the couple wasn't married.

Speaking again on behalf of others in his situation, he said, "We all tried to become parents. We went to great lengths to become parents. I had a surgery to become a parent … [but] I was unfairly deemed a donor with no recourse."

The bill, "doesn't give me my son back … [but] it gives standing for men to constitutionally get their rights and go into court and say, 'I'm the dad,' and let a judge decide if he's not," Patric added. "I haven't seen Gus in 25 weeks, and I just want you to think about that number in case you have a child or you've lost a child."

He's also concerned about the welfare of his son, whom he said could be "sitting daily, wondering what happened in the most severe form of alienation that one could imagine."

Patty Glaser, an attorney for Gus's mother, Schreiber, told ABC News a different story. Patric "was quite clear" prior to the child's conception and during Schreiber's pregnancy, she said, that he did not want to be a father. In fact, she claimed, Patric wanted his role in the pregnancy to be a secret.

"The moment they broke up, he demanded 50/50 custody," Glaser said. "She said, 'What are you talking about?' That doesn't make any sense. Being a parent is a big responsibility. You don't get to move in and out of parenting between acting jobs. It's a full-time job."

Glaser noted that the bill Patric was testifying about is on hold.

"If Jason Patric were the devil or a saint, irrespective of that conclusion, either way, the legislation needs fixing," she said. "It is vague, ambiguous and it's horrific for mothers. … Moms should have a say in this, and the legislation is drafted irrespective of what moms want. That's silly."