Back in December 2006 with his stint as Senate minority leader still fresh in mind, soon-to-be Majority Leader Harry Reid (D- Nev.) offered an olive branch to his Republican colleagues. Call it the Reid Doctrine.

"I will do my part as majority leader to foster respect for the rules and traditions of our great institution," he said. "I believe in the Golden Rule. I am going to treat my Republican colleagues the way that I expect to be treated."

One of those traditions is that senators follow a rigorous honor code built upon trust and honesty. Why? Because the Senate's respect for minority rights allows senators who object to controversial bills to invoke parliamentary devices to bring the entire body to a screeching halt, often for weeks at a time. If senators doubted their colleagues' integrity, negotiating solutions would be impossible.   

One of the most powerful tools a senator has is the "hold." This allows a senator who objects to pending legislation to single-handedly prevent a bill from being considered, and it usually prompts the bill's sponsors and Senate leaders to negotiate with him. Sometimes these negotiations convince the sponsor to amend the bill outright; more often it leads to "unanimous consent" agreements where the majority leader gives a bill's detractor a chance to raise his concerns on the floor in exchange for a promise to remove the hold.

The handshake that accompanies a unanimous consent agreement is sacrosanct.

Such was the case last Dec. 19, when Reid and Sen. Tom Coburn (R-Okla.) shook hands on an agreement. Reid agreed that Coburn could offer five unspecified but "related" amendments to a pork-laden federal lands bill. In exchange, Coburn agreed to remove his hold. Reid entered the terms of the agreement into the Congressional Record for all to see. No senator objected.

By "related," Reid meant that Coburn could offer only amendments that were germane or relevant to the bill in question. The agreement didn't specify which amendments would be allowed, nor did it limit the topics that Coburn could address. Reid no doubt assumed that, as the Senate's leading scourge of wasteful government spending, Coburn would focus on the bill's excessive costs. In fact, all but one of his amendments tackled this aspect of the bill.

But one of Coburn's amendments, while entirely germane, presented Reid with a nasty political dilemma. "The Secretary of the Interior," it read, "shall not promulgate or enforce any regulation that prohibits an individual from possessing a firearm in any unit of the National Park System or the National Wildlife Refuge System" so long as the individual is law-abiding and the state in which the park is located allows him to possess it. Interior Department regulations currently restrict firearms in national parks to those that are unloaded, disassembled and inaccessible. Under Coburn's amendment, the Second Amendment right to bear arms would finally be extended to visitors to our national parks.

Oops. The last thing Reid wanted during an election year was to expose the likely Democratic presidential nominee and Senate candidates to a tough vote on a Second Amendment issue, one that would no doubt split his Democratic colleagues and hand Republicans a high-profile legislative victory. But the only way to avoid this would be to walk away from a formal unanimous consent agreement. Senate veterans were hard-pressed to recall even one instance where a majority leader had resorted to so drastic a step.

To practitioners of the Golden Rule, the solution was obvious: Stick with the agreement. But on Feb. 8 Reid declared his agreement with Coburn null and void. A war of words ensued. Reid's spokesman lashed out at Coburn's amendment as a "shallow and transparent attempt … to score cheap, and I emphasize cheap, political points." Coburn's spokesman noted that "Dr. Coburn isn't responsible for the majority leader's inability to communicate the kind of deal he would like."

Reid's public betrayal of Coburn raises a legitimate question. Can any senator negotiate with him in good faith and expect him to live up to an agreement? As one ex-Senate aide colorfully put it: "In the Senate, at the end of the day you are only as good as your word. If Coburn hornswoggled Reid, then the remedy is not to break your word. It is to work harder so as not to get dickered again."

Or will suspicious senators begin to treat Reid the way he treated the good doctor from Oklahoma?

Michael Franc is Vice President of Government Relations for The Heritage Foundation.