"I really don't like the legal justification because it's not a legal justification at all," Lee said Tuesday in an interview on Laura Ingraham's radio show.
Ingraham then asked if it was constitutional for the U.S. to executive citizens abroad.
"I think it's fraught with constitutional problems," Lee said.
After NBC News published details of the memo, a number of lawmakers were quick to press the White House for more information on drone operations overseas. A bipartisan group of 11 senators sent a letter to the White House demanding more information on overseas drone strikes.
In response to the calls for more information, the White House announced it would brief members of Congress on classified details for when it can use drone strikes on U.S. citizens.