President Barak Obama wasn’t the first U.S. President to use an autopen when he signed the “fiscal cliff” legislation this month.  Presidents have relied on technology to help them perform their duties since the days of Thomas Jefferson.

Clearly a fan of technology, Jefferson was the first president to use the polygraph, a mechanical device that produced identical copies of handwritten letters. “The use of the polygraph has spoiled me for the old copying press the copies of which are hardly ever legible. . . . I could not, now therefore, live without the Polygraph," he wrote to a friend while in office.

As for its predecessor, the autopen, President Obama has actually used the device several times. It copies and stores a signor’s pen strokes for later use, which allows him to sign legislation without having to physically be in Washington, D.C. or having the bill couriered to and from his location. The President first used the autopen to sign an extension of the Patriot Act while attending a summit in Europe.

Of course, any time a President strays from tradition, questions of legality often arise. When President Obama first used the autopen, Rep. Tom Graves (R., Ga.) raised questions about whether the bill was truly “presented” to the President and asked for an explanation of its constitutionality. The use of the autopen, however, has never been officially challenged in court.

With regard to signing a bill into law, the U.S. Constitution simply states: "If he approve he shall sign it." It does not offer any guidelines regarding the means of signature.

When President George W. Bush was first presented with the option of the autopen, he asked the Department of Justice to prepare an opinion on whether it complied with the Constitution. As explained by the DOJ, “Neither the constitutional text nor the drafting and ratification debates provide further guidance regarding what it means for the President to 'sign' a bill he approves."

“The President need not personally perform the physical act of affixing his signature to a bill he approves and decides to sign in order for the bill to become law. Rather, the President may sign a bill within the meaning of Article I, Section 7 by directing a subordinate to affix the President's signature to such a bill, for example by autopen," the opinion concluded.

While its legality seems to be solidified, the White House still closely guards any information about it. Jack Shock, Bill Clinton's director of presidential letters and messages, once joked, "I always heard the autopen was the second-most guarded thing in the White House after the president."

Donald Scarinci is a managing partner at Lyndhurst, N.J. based law firm Scarinci Hollenbeck.  He is also the editor of the Constitutional Law Reporter and Government and Law blogs.