Jason Patric will be able to fight again to be legally recognised as the father of his 4 year-old son, Gus.
The actor, whose victory occurred in a Los Angeles courtroom, will take the custody case back to trial after losing an earlier bout in February last year (2013).
Patric fathered the young boy by in-vitro fertilization, or IVF, with his then girlfriend, Danielle Schreiber, and they both co-parented him until their relationship ended in 2012.
But due to the 47 year-old conceiving the child through a sperm donation, an early court decided he was only a sperm donor to Schreiber, and therefore had no parental rights to Gus.
However, California appeals court judge Thomas Willhite says that the presumption against in vitro fathers shouldn't be "so categorical," and that the family law code "does not preclude a donor from establishing that he is a presumed father," via The Hollywood Reporter.
Patric and Schreiber have been dating on-and-off for about ten years, but split for good in 2012, shortly after this he filed a paternity claim.
While in court, Schreiber attempted to forbid Patric from seeing their son, and the judge at the time used a 2005 California appellate case (Steven S. v. Deborah D.) to grant the mother the victory in February 2013.
"I don't think anyone is going to prevail as a result of this," the judge said at the time. "I think at the end of the day that everyone turns out to be worse off, and certainly I think Gus turns out to be worse off as a result of where we're going to end up. But it just is what it is, because I think that's the legislative policy that's been articulated."
Following this, Patric filed an appeal which has led to Wednesday's decision.
MORE: Jason Patric Testifies For Custody Of His Son
The judge's rule concluded with: "a sperm donor who has established a familial relationship with the child, and has demonstrated a commitment to the child and the child's welfare, can be found to be a presumed parent even though he could not establish paternity based upon his biological connection to the child."
MORE: Jason Patric's Ex-girlfriend Granted Restraining Order Against Him
This does not give Patric parenting rights, but it does allow him a chance to fight for custody in court.
Patric won his appeal on Wednesday