Joel Goldstein

Pence has taken care to appear extraordinarily loyal to Trump, so much so that Joel K. Goldstein, a historian and an expert on Vice-Presidents who teaches law at St. Louis University, refers to him as the “Sycophant-in-Chief.”

- The Danger of President Pence

The modern-day vice president serves primarily as a close presidential adviser and assistant. The vice president’s move from Capitol Hill to the White House has allowed the office to become a significant institution. But this week, Mike Pence reminded Americans of an older role the vice president also sometimes serves: that of legislative officer who can preside over the Senate.

- Mike Pence, the Tie Breaker

No other powers are specified, but in reality “the office has grown into a central part of the presidency,” says Saint Louis University law professor Joel Goldstein. The vice president serves as an “across-the-board adviser and troubleshooter.”

- What do U.S. vice presidents do?

The amendment’s principal author, Sen. Birch Bayh, D.-Ind., embraced an understanding that presidential inability would encompass both physical and mental inability, said Joel Goldstein, a law professor at St. Louis University, who’s closely studied the congressional record.

- When can the 25th Amendment be used against a president?