You need to read your Bible. The Pharisees were exactly the type of people who would have used libel laws against Jesus. They were rule-bound priests who utilized an oral tradition of man-made laws to nitpick Jesus with technically accurate accusations of blasphemy.
And in fact, one of the main accusations the Pharisees made against Jesus before Pilate could almost be said to be in the nature of a libel accusation. Specifically, the Pharisees accused Jesus of claiming to be the 'King of the Jews.' And it was that claim which Pilate based his sentence of crucifixion on. So Jesus was crucified for merely saying things which could not be proven in the way that Pilate expected them to be proven.
In any event, when Jesus was falsely accused of things, his response wasn't to resort to the law like the Pharisees did when they brought him before Pilate. Instead, Jesus' response was to meet words with words. And that is how Jesus dealt with the Pharisees, by arguing against their positions and pointing out to people the hypocrisy of the arguments they were making against him.
Oh, really?
Luk 23:2 And they began to accuse him, saying, We found this fellow perverting the nation, and forbidding to give tribute to Caesar, saying that he himself is Christ a King.But of course, your defense of slander and lies is in keeping with the best of moral precepts and rectitude....Luk 23:14 Said unto them, Ye have brought this man unto me, as one that perverteth the people: and, behold, I, having examined him before you, have found no fault in this man touching those things whereof ye accuse him