Oregon's assisted suicide law, the only one in the nation, has survived numerous challenges.
He emphasized, however, that the state was right to prosecute Mr. Williams under its assisted suicide law.
In this state, supporters of the suicide law say they will go to court to halt any attempt by the Federal Government to sanction doctors.
The legislation is intended to overturn Oregon's assisted suicide law.
A federal judge in Oregon yesterday rejected an effort by the Justice Department to block the state's assisted suicide law.
Oregon enacted its assisted suicide law six years ago.
The Netherlands has the most liberal assisted suicide laws in the world.
The Bush administration's position has discouraged other states from enacting assisted suicide laws.
In each of the four previous trials he was charged with violating assisted suicide laws, not with committing murder.
In 1994, voters in an Oregon referendum approved a doctor-assisted suicide law by a margin of 51 to 49 percent.