Here's Jeff Sessions,  of all people, questioning Yates during her Senate confirmation hearing in 2015:

"Sessions: You have to watch out, because people will be asking you to do things that you just need to say no about. Do you think the attorney general has a responsibility to say no to the president if he asks for something that’s improper? A lot of people defended the [Loretta] Lynch nomination by saying well, [then-President Obama] appoints somebody who’s going to execute his views. What’s wrong with that? But if the views that the president wants to execute are unlawful, should the attorney general or the deputy attorney general say no?

Yates: Senator, I believe that the attorney general or the deputy attorney general has an obligation to follow the law and the Constitution, and to give their independent legal advice to the president."

Sessions like the answer, but he didn't know the president would be Trump.