Under the constitution, the judicial branch must try criminal cases with a blank of one's peers

The correct answer is a jury of one's peers.

In a criminal case, the person accused of a crime has the right to have their case conducted in front of a jury of their peers. The jury will listen to both the defense and prosecution in order to fully understand the event in question. From there, the jury will determine whether or not the person is innocent or guilty. This legal protection ensures that the government does not have unlimited power in the legal system.

I think the word you're looking for is either "jury" or "panel".