President Barack Obama signed the bill to avert the so-called fiscal cliff, but he didn't do it in person: An autopen was utilized to sign the dotted line.
Via the White House pool report on location for the president's vacation in Hawaii:
"The fiscal cliff bill was received late this afternoon when POTUS was already here. A copy was delivered to POTUS. He reviewed the copy and directed the legislation to be signed by auto pen."
The president has utilized the mass signature facsimile machine before, but not without drawing criticism. Remember what happened in 2011? President Obama used an autopen to sign the Patriot Act in the summer of that year—a method the White House and others say is completely legal.
But House Republicans got together and called on the president to sign the act again in person. They and others questioned the constitutionality of the autopen.
So how did that controversy end up? The president did not re-sign the law.