Opponents of health care reform have raised the specter of government-subsidized illegal immigrants flooding our medical system with their costly illnesses. In fact, as I’ve reported before and the Migration Policy Institute notes today, the real problem is that health care proposals now under consideration in Congress would drive up the nation’s health care costs by leaving many legal immigrants uninsured and reliant on costly emergency room visits and public health clinics. And because legal immigrants tend to be younger and healthier and have fewer medical needs than the average U.S. citizen, excluding them from the health insurance pool would end up costing U.S. taxpayers more, rather than less, in the long run.

According to MPI, of an estimated 12 million lawful permanent residents in the United States, 4.2 million are uninsured and more than 1 million would be excluded from Medicaid coverage or insurance subsidies if Congress doesn’t remove the current five-year waiting period for eligibility, which current proposals do not do. Legal immigrants would still be required to purchase coverage, though, putting them at a significant disadvantage compared to the rest of the legal population.

“Leaving large numbers of legal immigrants out of health care reform would defeat the core goal of the legislation, which is to extend coverage to the nation’s 46 million uninsured,” said MPI Senior Vice President Michael Fix in a statement released with the report today.

The report also criticizes the proposals for stringent eligibility screening, which is often costly and badly designed, and keeps eligible U.S. citizens from getting access to medical coverage if they can’t prove their citizenship. The Brennan Center for Justice found that in 2006, 21 million U.S. citizens lacked valid identity documents necessary to prove their citizenship.