GOP rep: Where in the Constitution does it say you can sign bills by autopen?

“Mr. President, I write to request your confirmation that S. 990, as passed by Congress, was presented to you prior to the autopen signing, as well as a detailed, written explanation of your Constitutional authority to assign a surrogate the responsibility of signing bills passed into law,” Graves wrote.

Obama signed the bill into law late Thursday night. The autopen was used because the president was in France, meeting with G8 leaders, and the bill’s provisions expired at midnight.