Introduction to Tractate Sanhedrin
Tractate Sanhedrin contains mostly laws concerning courts and court procedure, with much of the discussion revolving around courts that had to adjudicate capital cases. The word Sanhedrin, which is a Greek word (and is preserved in the English word synod), signified a large council of Sages, and during the times of the Temple (until 70 A.D.) it met in the Temple itself, in the Chamber of Hewn Stone. It is also known to have existed during the Second Temple period from non-Jewish sources (the Christian Bible, Greek writings, Josephus, etc.). Tractate Sanhedrin in the Mishnah does not deal with these types of historical issues; rather it deals with legal issues: the procedure of the court, selection of judges, the testimony of witnesses, lists of punishments and other issues. There is also an important chapter which we will learn towards the end of the tractate dealing with theological issues of the world to come.
One important note to make is that many of the laws in Tractate Sanhedrin were only theoretical already in the time of the Mishnah. The Rabbis rarely if ever carried out the death penalty and therefore most of the discussions concerning for which crimes one receives the death penalty and how different types of executions were performed were theoretical for the Rabbis. Nevertheless, Tractate Sanhedrin does contain important and interesting information with regards to central issues that still concern us today.