When we go to court and the prosecutor has a key witness ready to testify against us, we basically have only three options of things we can do.
One, we can make the witness disappear, much like Don Corleone in the Godfather. Or, two, we can try to discredit the witness by digging up dirt on his past sins that would impugn his testimony and character. In other words, we would put the witness on trial. And if that didn't work, three, we could hire Madison Avenue lawyers to find a technicality, a loophole, to get us off.
This is exactly the course of action the Pharisees plotted against Jesus, to no avail. Why? Because He was always one step ahead of them.