Proponents of medical marijuana had hoped to gain momentum following the high court's ruling. A poll commissioned by the Marijuana Policy Project found that respondents, by a 68-18 percent margin, believe that medical marijuana users should not face federal prosecution.

By a 264-161 vote, the House turned down an amendment that would have blocked the Justice Department from prosecuting people in the 10 states where the practice is legal.

Advocates say it is the only way that many chronically ill people, such as AIDS and cancer patients, can relieve their symptoms.

"It is unconscionable that we in Congress could possibly presume to tell a patient that he or she cannot use the only medication that has proven to combat the pain and symptoms associated with a devastating illness," said Rep. Maurice Hinchey, D-N.Y.

'Serious Mental Health Problems'

Opponents of the amendment said it would undercut efforts to combat marijuana abuse. They said Marinol, a government-approved prescription drug that contains the active ingredient in marijuana, offers comparable relief.

"Marijuana has never been proven as safe and effective for any disease," said Rep. Mark Souder, R-Ind. "Marijuana can increase the risk of serious mental health problems, and in teens, marijuana use can lead to depression, thoughts of suicide, and schizophrenia."

The vote came as the House debated a $57.5 billion bill covering the departments of Commerce, Justice and State.

Proponents of medical marijuana had hoped to gain momentum following the high court's ruling. A poll commissioned by the Marijuana Policy Project found that respondents, by a 68-18 percent margin, believe that medical marijuana users should not face federal prosecution.

The poll, conducted June 8-11 by Mason-Dixon Polling & Research, also found that 65 percent of those surveyed favored doctor-prescribed medical marijuana, with 20 percent opposed.

A similar amendment last year was defeated by a comparable margin.

"A lot of these guys voting against it are just afraid because it's a 'drug issue,'" said Rep. Sam Farr, D-Calif.

Display of the Ten Commandments

In a wide-ranging debate, the House also voted again to support the display of the Ten Commandments on the grounds of government building and narrowly rejected an amendment to block restrictions on gift parcels shipped to Cuba.

By a 242-182 vote, the House approved an amendment by John Hostettler, R-Ind., to block the government from carrying out a federal judge's order that a monument on a courthouse lawn in his district representing the Ten Commandments be removed as a violation of the prohibition between church and state.

The 216-210 vote on Cuba reversed a trend in recent years of rising sentiment in Congress in favor of relaxing penalties against Cuba. The House passed a similar amendment last year by a 221-194 vote.

At issue are tighter restrictions imposed a year ago on package shipments, including those sent to Cubans by people in the US.

"We are not going to prop up the regime in Cuba by sending toothpaste and toilet paper," said Rep. Jeff Flake, R-Ariz.

A White House policy statement said: "It is essential to maintain sanctions and travel restrictions to deny economic resources to the brutal" rule of President Fidel Castro.