At midnight tonight, God willing, Senator Byrd will become the longest-serving congressman ever. I’d forgotten that he’s president pro tempore of the Senate, and thus third in line for the presidency. But considering that he turns 92 on Friday, I wonder: Can the president pro tempore, or the veep or speaker of the House (or secretary of agriculture, if it comes to that) turn down the job if it were to fall to him in the event of a catastrophe? In The Man, James Earl Jones was president pro tempore and only became president because the vice president turned the job down due to illness. The Constitution only spells out how a president can be declared incapacitated by the cabinet; does the law on presidential succession address this?