Is character assassination legal

The Defendant's character in and of itself is not on trial during a criminal proceeding. Whether or not the defendant is kind of a jerk or known for being dishonest is not evidence that he committed the crime at question, and is generally inadmissible.

However, the defendant may open the door for the prosecution to introduce evidence of his bad character. For example, if the defendant is charged with embezzling funds, and the defendant introduces character evidence to show that he is a generally honest person, the prosecution may then rebut that evidence by introducing evidence that the defendant is a liar.