Senators know a bad law when they vote for it. In an act of rank hypocrisy, they've joined their colleagues in the House of Representatives in pushing legislation that would exempt federal retirees (including retired senators) from the Medicare prescription-drug bill they voted to apply to millions of senior citizens in the private sector.

The drug legislation now in a Capitol Hill committee would create a universal drug entitlement for all seniors in Medicare. Sounds great, but there's one little problem: 78 percent of seniors already have drug coverage, mostly through former employers. What will happen to them?

More than one out of every three seniors with coverage through their former employer would be dumped out of that coverage and into the new government drug program, according to the Congressional Budget Office. They will wind up paying more for an inferior benefit. A Heritage Foundation analysis of data supplied by the Senate Budget Committee shows that the average senior would see an increase of nearly 60 percent in out-of-pocket expenses under the Senate-passed plan compared to what he or she is paying now. But it gets worse.

Not only will more than 4 million seniors lose their current coverage, but another 4.8 million seniors who buy supplemental insurance to help with drug costs would find out that the Senate bill undercuts this "Medigap" coverage. So millions of seniors would lose their existing drug coverage or find that it's sharply scaled back. It doesn't matter that they've worked and paid for it, either directly out of their own pockets or through deferred compensation on the promise of employer coverage.

But if powerful senators have their way, this won't happen to retired federal workers and members of Congress.

Republican Sens. John Warner and George Allen of Virginia, along with Democratic Sens. Paul Sarbanes and Barbara Mikulski of Maryland and Sen. Daniel Akaka of Hawaii are co-sponsoring a bill that would protect their retired colleagues and federal retirees from the impact of same Medicare bill that all but one of them (Sarbanes) voted for last month.

Here's something even more curious. Every one of these senators, now pushing for special protection for federal retirees and retired members of Congress, voted -- on the record -- last month to cast their own lot with seniors in the private sector. Sen. Mark Dayton, D-Minn., offered an amendment to the Senate Medicare bill that would have required members of Congress to have the same level of prescription drug coverage they were designing for the rest of America's seniors.

The Senate passed the Dayton amendment, 93-3. It turns out, though, that this lopsided vote was a cynical act of showmanship. As an anonymous Senate GOP staffer told Roll Call newspaper: "The staff will make sure it fails even before we get to the conference."

This senatorial sleight of hand is understandable. The backers of the bill have many current and retired federal employees among their constituents, and these folks have a good thing going. They're covered by the successful Federal Employees Health Benefits Program (FEHBP), which means they can choose from at least a dozen private health plans and solid drug coverage. President Bush himself has cited the federal employees' program as a model for Medicare reform.

To be fair, Rep. Bill Thomas, R-Calif., and most of his colleagues on the House Ways and Means Committee do favor that model for Medicare. In the House bill, there is a provision that would begin Medicare's transition to an FEHBP-style Medicare program -- but not until 2010.

Still, 196 members of the House of Representatives are on record opposing that transition to an FEHBP-like system, and 37 senators say that a transition to a competitive system is unacceptable in any final bill. In other words, they're enrolled in a superior health plan, with reliable drug coverage, whose replication for the retiring baby boomers they steadfastly oppose. Mysterious.

These congressional gyrations on drug coverage are hard to follow. But there's a way to figure out the basics: Pay little or no attention to what members of Congress say. Instead, watch what they do.

In the case of the Medicare drug benefit, one clear message coming out of Congress is this: Government-run medicine may be OK for all the little people, but not for us, thank you very much. They clearly want no part of their own Medicare handiwork to affect their own coverage in retirement.

That tells you a lot about the value of the proposed Medicare drug benefit.

Robert Moffit is director of the Center for Health Policy Studies at The Heritage Foundation, where Derek Hunter is a researcher.