I read your answer and disagree. Paul was of the tribe of Benjamin and to qualify to judge criminal cases he had to be legally married to the daughter of a priest. Paul's job under the high priest was to root out the Christians. Look at the second small paragraph in the Tractate Sanhedrin. If I am mistaken I would like to know.
Let me first note that you provided no scriptural evidence. Instead you make conjectures. You assume Paul had the right to judge criminal cases. "Then Saul, still breathing threats and murder against the disciples of the Lord, went to the high priest and asked letters from him to the synagogues of Damascus, so that if he found any who were of the Way, whether men or women, he might bring them bound to Jerusalem" (Acts 9:1-2). Paul was given permission to arrest Christians, but he was bringing them back to Jerusalem, which implies they would be judged in Jerusalem.
Next, "All are qualified to judge civil cases, but not every one is qualified to judge criminal cases; as to the latter -- only priests, Levites, and Israelites who may legally marry daughters of priests" [Tractate Sanhedrin]. Notice that only those who are priests who could legally marry a daughter of a priest could judge criminal cases by Jewish law (not necessarily God's law). But it doesn't say the person had to be married to a priest's daughter, just potentially able to marry such a person.
But really all of this is completely foolish because you have Paul's own words that he wasn't married. "But I say to the unmarried and to the widows: It is good for them if they remain even as I am" (I Corinthians 7:8). The arrogance of people living 2,000 years after these events who think they know more than a person's own account is amazing.