Toulouse - South-African-born French international Scott Spedding, who has taken the French league to court, has signed with Castres for next season, the club announced on Thursday.
Spedding, who is 32 and has played 23 times for France at fullback, has just been released by Clermont, where he had played since 2015.
The player anticipated the move, blamed stricter rules on non-French players in the Ligue nationale de rugby (LNR) and in April took the matter to the Conseil D'Etat, France's Supreme Court.
In an attempt to force French clubs to field more players eligible for the national team, the LNR created a category of French-reared players, known as JIFFs (joueurs issus des filires de formation), who must have been registered with the French Rugby Federation for at least five years or have spent three seasons in a federation-approved academy if they are under 21.
To avoid breaking EU laws, the rules do not specify that players have to be of French nationality.
Spedding holds a French passport, but only moved to France at the age of 22, when he joined Brive, and fails to qualify as a JIFF.
The LNR have been progressively tightening the rules, threatening to dock points from teams who don't average 60 percent of JIFF players on team sheets. A decision in February to increase the minimum on each team sheet from 14 to 15 next season, brought a legal reaction from Spedding.
He argued that the decision prevented him "finding an employer" for next season.
The Conseil D'Etat started considering the case earlier this month, as Spedding, who reportedly had offers from English clubs, found a team in France.