The directive by U.S. Attorney General John Ashcroft had reversed a Clinton administration decision to allow physicians in the state of Oregon to ignore federal law and prescribe lethal doses of federally controlled substances.
The Wednesday decision, by a panel of the 9th Circuit Court of Appeals, in the case of Oregon v. Ashcroft will likely be appealed to the U.S. Supreme Court.
"Suicide among the elderly and those suffering from serious illness or disability is not a 'medical practice' but a tragic public health problem deserving a thoughtful, caring response," said Cathy Cleaver Ruse, spokeswoman for the U.S. bishops' conference Pro-Life Secretariat.
"The 9th Circuit has just told these patients that their lives are expendable," she said in a statement.
The Ashcroft directive restores the uniform enforcement of the long-standing federal Controlled Substances Act, and also clarifies that aggressive pain management is legitimate medical care even where it unintentionally increases the likelihood of a patient's death.
"This is not about an attempt by the attorney general to control Oregon law," Ruse said. "Rather, it's about whether Oregon should be able to ignore federal law and at the same time co-opt the federal government into facilitating assisted suicides by providing federal prescribing licenses and federally controlled drugs."