Those who say yes point to some very bad choices he made, including drunkenly bragging to a Navy commander that he would steal replacement sails and rigging for his ship, the Adventure Galley, if he felt like it. He also failed to control his crew of former and not-so-former pirates who were on the brink of mutiny and overly eager to get paid for their share of goods seized, legally or not.
Those who agree with Kidd's words that he was "the most innocent of pirates" point to a French pass carried by the Quedah Merchant, making the ship a legal war prize for any English vessel at the time. And they cite language in Kidd's commission as a privateer which gave him the right to seize and "condemn" such vessels.
And even some who say he was guilty concede that his trial set a new low-water mark for politically-influenced justice in early 18th century England.