A day that began with the outgoing president’s pardon of lawmakers and his own family ended with the incoming president’s pardon of supporters who attacked the U.S.

The extraordinary wave of pardons Monday — from Joe Biden as he left the White House and from Donald Trump as soon as he returned to it — demonstrate the potency of the Constitution’s pardon power, but also expose its perils,

Biden Monday issued several preemptive pardons, some to family members. Following the transition of power, Trump wielded his own clemency power.