Mel Gibson lost a round in court after arguing that Oksana Grigorieva should be stripped of custody because she allegedly leaked info to TMZ.
Sources connected with the case tell us ... Mel's lawyers argued to Judge Scott Gordon last week ... Oksana was not acting in the best interests of Lucia by allegedly telling TMZ what she said during her deposition.
TMZ broke the story ... Oksana claimed during her deposition that Mel beat her during sex.
Grigorieva denied leaking the info to us -- and Mel's lawyers responded by getting declarations from everyone else in the case stating they weren't the leak ... so, they said, it had to be Oksana.
In the end, Judge Gordon told everyone to go home, insisting who-leaked-what was irrelevant to child custody.