Now that the Senate has passed its version of health care reform along partisan lines, let's look ahead to the single biggest issue that will draw the most heat in conference: The tax on so-called "Cadillac plans," the largest revenue raiser in the Senate legislation.

As regular readers of this blog know, I consider it ill-considered and unfair, a tax on people stuck in expensive plans because they belong to groups with older and sicker beneficiaries who use more health services; small groups generally; or who live in areas with expensive delivery systems. The idea that taxing those plans will somehow encourage people to reduce their utilization is wishful thinking that ignores who actually makes health care decisions -- doctors, hospitals,  drug companies, and other providers.

It also ignores why most people use health care -- it's because they are sick. The latest research shows less than 4% of the higher cost of some plans is due to extra benefits. Most of the rest is due to the higher claims of people in those more expensive plans, or the fact that the plans cover people in areas with expensive medicine.

To the extent taxing the excess costs will work in getting people to reduce utilization, the studies shows beneficiaries are just as likely to eliminate needed care like preventive medicine as they are to reduce wasteful spending, which is, don't forget, ordered by their physician or the hospitals, who are the primary drivers of the health care train. The tax will do nothing to make providers more efficient or effective in their use of system resources.

Nor will it force insurers to be more circumspect in what they will pay for. Ever since the patients rights rebellion of the late 1990s, they have become nothing more than pass-through agents in the system, taking their cut off the top. That's what they'll do with the tax -- pass it along to employers, who in turn will pass it along to their employees.

The economists who argue for this tax ignore all the dysfunctional realities of the health care "marketplace" that I have just described. Those realities make cost control measures that rely on incentive tinkering -- and this tax is a prime example -- doomed to failure.

In the end, it's just another tax, one that largely falls on the middle class. Sadly, President Obama rotely repeted the economists' logic in his interview with NPR yesterday.

In yesterday's Roll Call, Washington & Lee health law professor Timothy Jost and Case Western Reserve professor Joseph White (a biostatistician and epidemiologist) laid out the case against the tax and offered a logical compromise because they assume, no doubt accurately, that some version needs to be included in the final bill to satisfy both the Senate and the president's desire that every idea for cost control (even bad ones) be included. They suggest the tax should only be levied on benefits that exceed the premium standard package offered in the exchanges. Then it will truly be a "Cadillac" tax.

Unfortunately, an accurately circumscribed Cadillac tax won't raise much money. That's why the House bill is far preferable when it comes to taxation. In the end, this debate is about who is going to pay the higher taxes to provide for the uninsured, not health care cost control. And when it comes to that question, I say -- and I dare say hundreds of millions of Americans would agree -- that after the past two decades experiment in income maldistribution, the time has come to levy more taxes on higher income households, not on people who are older, sicker and already struggling to pay their bills.