John Lightfoot on John 9:13

[They brought him to the Pharisees.] The Pharisees, in this evangelist, are generally to be understood the Sanhedrim: nor indeed do we find in St. John any mention of the Sadducees at all. Consult John 1:24, 4:1, 8:3, 11:46, &c.

The Pharisees have such a sway amongst the people, that if they should say any thing against the king or high priest, they would be believed. And a little after,

"The Pharisees have given out many rules to the people from the traditions of the fathers which are not written in the laws of Moses: and for that very reason the Sadducees rejected them, saying, They ought to account nothing as law or obligatory but what is delivered by Moses; and what hath no other authority but tradition only ought not to be observed. And hence have arisen questions and mighty controversies; the Sadducees drawing after them the richer sort only, while the multitude followed and adhered to the Pharisees."

Hence we may apprehend the reason why the whole Sanhedrim is sometimes comprehended under the name of the Pharisees; because the common people and the main body of that nation were wholly at the management of the Pharisees, governed by their decrees and laws. But there was once a Sanhedrim that consisted chiefly of the sect of the Sadducees, and what was done then? R. Eliezer Ben Zadok saith, There was a time when they burnt a priest's daughter for whoredom, compassing her about with bundles of young twigs. But the answer is, There was not a Sanhedrim at that time that was well skilled. Rabh Joseph saith, "that Sanhedrim was made up of Sadducees." It is worth our taking notice of this passage.