U.S. Treasury Secretary Timothy Geithner holds up a copy of the U.S. Constitution before reading a passage from the 14th Amendment during a breakfast interview at the Newseum in Washington, May 25, 2011. (JONATHAN ERNST/REUTERS)

In honor of Constitution Day we pose the question: Which part of the Constitution governs the use of laser pointers?

It sounds like a dumb question, since the Constitution predated the laser by 171 years. But this year, the House of Representatives declared it had found an answer: Article I, Section 8, Clause 3.

That clause says Congress has the power “To regulate Commerce ... among the several States.” Which, of course, doesn’t say anything about lasers. But the House still used those words to justify a bill that prohibited pointing lasers at aircraft: The logic was that they were acting to protect “commerce.”

This legal loop-de-loop is the result of a new rule in the House, where Republican leaders require every bill to carry a “Constitutional Authority Statement.” The idea was to demonstrate that a new GOP majority respected the enduring restraints of the Constitution.

Instead, this Congress has often demonstrated something else: an ongoing tendency to make the Constitution say whatever they want it to.

Over nine months, the House has passed laws about a variety of modern issues that the Founders didn’t mention — abortion, charter schools and lasers. For authority, they have often turned to broad clauses about “commerce,” the “general welfare,” and the need for “necessary and proper” laws.

That’s not necessarily wrong. But — as the country observes Constitution Day Saturday — it has left some conservatives wondering if their message has sunk in.“They’re generally pretty loosey-goosey,” said Matthew Spalding, a scholar at the conservative Heritage Foundation. “I’ve not seen any evidence yet that it’s really causing the average lawmaker to spend any time thinking about Constitutional limitations.”

Republicans promised to make this change before last fall’s elections, in the party’s “Pledge to America.” Their message was tailored especially to tea party groups, who felt the health care law had expanded federal power far beyond what the Founders intended.

“For too long,” the GOP said, “Congress has ignored the proper limits imposed by the Constitution on the federal government.”

So, when they took over the House, Republicans imposed a new rule: Each bill would carry a “statement citing as specifically as practicable the power or powers granted to Congress in the Constitution” to enact it. The Democrat-held Senate has no such rule.

Nine months later, Republican leaders say the policy is not perfect, but it has done something valuable: require legislators to constantly check themselves against the Constitution.

“I think it’s a useful exercise — it is a reminder of the importance of our most important document,” said Rep. Greg Walden (R-Ore.), a top ally of Boehner’s.

Has the new rule actually altered the substance of bills, to make them consistent with a limited-government philosophy? “Probably,” Walden said. “But I can’t point to any specific examples.”

Still, a review of the 98 bills with “authority statements” that have passed by the House this year shows a complicated picture.

Some bills — especially those introduced at the beginning of the year — contain detailed Constitutional justifications. H.R. 2, a bill to repeal the health care law, cited Articles 1, 2, 3, and 6, the 10th Amendment, and added a quote from James Madison for good measure.

But, in other cases, the House approved bills whose “authority statements” were scanty, and reliant on the same sweeping clauses that conservatives had bashed liberals for using in the past.

H.R. 525, for instance, expanded federal aid programs aimed at public health workers: under the new rule, veterinarians would also be eligible.

The Constitution, of course, says nothing about veterinarians. But the bill’s sponsor, Rep. Tammy Baldwin (D-Wis.) still found a justification: She cited the clause about “commerce,” and another one that lets Congress make all laws “necessary and proper” to carry out its responsibilities.

How did Baldwin decide that was enough? A spokeswoman declined to comment: “Congresswoman Baldwin is focusing on creating jobs and strengthening the middle class.”

In H.R. 2218, which passed this week, the House altered an existing program that provides grants to charter schools. Charter schools — indeed, any kind of schools — are not mentioned in the Constitution.

So where did the House get the authority to regulate them now? Rep. Duncan Hunter (R-Calif.), the bill’s sponsor, cited Article I, Section 8.

“Well, that’s everything,” said Akhil Reed Amar, an expert on the Constitution at Yale University. Section 8 is a long list of everything Congress is allowed to do.“So that’s not specific.”

A spokesman for Hunter defended the citation, saying that Hunter had relied particularly on the part of that section that allows Congress to make rules providing for “the general welfare.”

Constitutional scholars say there’s a lesson here — even if it isn’t the one the House set out to send.

The lesson is that the Constitution isn’t a cake recipe: It’s not a precise, specific set of instructions for making a democracy. Instead, the great charter is vague enough that Americans have spent the last 224 years arguing about what it means.

The document, for instance, contains some broad phrases that seem to extend the federal government’s power — like the ones giving Congress authority to promote the “general welfare,” and pass laws it deems “necessary and proper.” The “commerce” clause has also been used to extend federal authority: It was used by the Obama administration to defend the health care law, on the grounds that health care is commerce.

But the Constitution also contains other passages that seem rein in federal power: The 10th Amendment, for instance, says powers not delegated to the federal government are reserved by the states and the people.

Some conservatives say they’re disappointed that the current Congress still seems to be paying too much attention to the former — and too little to the latter.

“It worked out essentially as I anticipated it would,” said Rep. E. Scott Garrett (R-N.J.), the head of the Congressional Constitution Caucus. Garrett had pressed for a more restrictive version of the rule, which would ban members from citing the “necessary and proper” and “general welfare” clauses. He said the GOP leadership shot it down.

Now, Garrett said, the use of these clauses by other legislators “shows to me that they could not really find a distinct Constitutional basis for their legislation, and they covered it over.”

Still, Garrett said the rule was a lot better than nothing: “It’s a great first step.”

There was a similar feeling in Georgia, where Virginia Galloway was making preparations for Sunday’s second annual Constitution Day Festival in Marietta. This event, like others around the country, celebrates the annivesary of its signing on Sept. 17, 1787.

“You now how the politicians say, ‘At least they’re talking about me now’” in the middle of a scandal?, said Galloway, the state director of the Americans for Prosperity Foundation. “The Constitution can say that now.”

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