Subject: Who gets the call?

My partner and I were playing a USTA mixed doubles match on clay. When our opponents returned a shot, I called it out, my partner called it good, then we walked over to the mark and it was out. However, the opponent argued that since we both called differently, the point was theirs, regardless of the mark in the clay. My partner, who's played many years longer than I said his men's teams have always let the mark in the clay decide the call. What is the protocol in this situation?

KAUFMAN: Your partner should have said nothing, and since he/she did not, doubt should now be resolved in favor of the opponents.  The opponents had a right to stop play when they heard the out call and play can not be resumed because a partner thought (correctly) the ball was in.  An erroneous call thus disrupted the point, and The Code has it right that the partners should talk privately and then concede the point since there was disagreement. 

With the disagreement that the opponents witnessed, they now may be some legitimate doubt on the mark you both decided to check.  Therefore, whether on clay or hard courts, when partners disagree, the opponents receive the benefit of the doubt.

The Code #14, Friend at Court (page 47)