The new policy also threatened to criminally prosecute doctors who recommend medical marijuana, and to exclude from Medicare and Medicaid.
The officials said the letter was intended to clarify a Clinton Administration plan to prosecute doctors who prescribed or recommended the use of marijuana to patients.
It failed to prosecute erring doctors and hospital.
This law codifies the twenty-year-old convention of not prosecuting doctors who have committed euthanasia in very specific cases, under very specific circumstances.
The case, Gonzales v. Oregon, is about the efforts by the Department of Justice to prosecute doctors who prescribe suicide drugs under the Oregon law.
Criminalization will sweep well beyond the Bible Belt: Ohio could be among the first to drive young women to back-alley abortions and prosecute doctors.
He also said it would be far more difficult to prosecute doctors whose offices file false claims.
But the Bush administration has tried to override this law by threatening to prosecute doctors involved in such cases.
They've been prosecuting doctors for prescribing painkillers like OxyContin, even where there's no evidence of any of the drugs being resold on the streets.
And the Clinton Administration has moved to shut down marijuana buyers' clubs in California and has threatened to prosecute doctors who write prescriptions for the drug.