By David Ingram
WASHINGTON (Reuters) - Overcrowding in U.S. federal prisons is so severe that the problem could go on for years even if Congress takes steps to reduce the number of people behind bars, according to a report released on Tuesday.
But the report from the nonprofit Urban Institute said lawmakers have many options available to start making dents in a prison population that by one ranking is the largest in the world.
The United States incarcerated 2.2 million people in state and federal institutions in 2011, the most recent year for which the U.S. Bureau of Justice Statistics has published data.
That tops prison populations in all other countries, according to data collected by the International Centre for Prison Studies in London. The center says, though, that its total for China does not include pre-sentence detainees, which may push that country's count into the top spot.
The huge prison population in the United States results largely from mandatory prison terms enacted in the 1980s and 1990s when crime was on the rise. Those policies are increasingly falling out of favor because of the expense and the social effects of locking up people who are disproportionately members of racial minorities.
Unusual pairings of liberal lawmakers and Tea Party movement conservatives are pushing legislation to reduce federal prison terms or give judges more flexibility in sentencing.
The report from the Urban Institute, a research group with roots in President Lyndon Johnson's Great Society anti-poverty program of the 1960s, shows how difficult it would be to bring the prison population in line with capacity.
Even if Congress were to cut mandatory minimum sentences for drug crimes by half, an idea with dubious political prospects, federal prisons would still be 20 percent above capacity in 10 years, the report said. They would be 55 percent above capacity if policies went unchanged, it said.
"As much as there are many good policy ideas out there, it's going to take several of them to even get to the point where prisons are not overcrowded," said Nancy La Vigne, director of the Urban Institute's Justice Policy Center.
The report also details the potential budget savings from a menu of changes under discussion in Congress.
If lawmakers were to apply retroactively new prison terms that they approved in 2010 for crack cocaine-related crimes, they would cut prison spending by $229 million over 10 years and free up 22,000 "bed-years." One person released 12 months early frees up one bed-year.
La Vigne is one of six witnesses invited to testify about a prison overhaul on Wednesday before the U.S. Senate Judiciary Committee. Others scheduled to appear include Charles Samuels, director of the Federal Bureau of Prisons, and officials from Kentucky and Pennsylvania.
The issue is a priority for U.S. Attorney General Eric Holder, who on Tuesday was scheduled to visit a Philadelphia program designed to reduce recidivism.
"There's been a tendency in the past to mete out sentences that frankly are excessive," Holder said at a news conference on Monday. Given financial constraints, he said, "we have to really rethink our priorities."
(Editing by Howard Goller, Andre Grenon and Vicki Allen)