SAN FRANCISCO/WASHINGTON (Reuters) - The Obama administration unveiled steps on Monday to fix what it considers the longstanding unjust treatment of many nonviolent drug offenders, aiming to bypass tough mandatory prison terms while reducing America’s huge prison population and saving billions of dollars.

“Too many Americans go to too many prisons for far too long, and for no truly good law enforcement reason,” Attorney General Eric Holder, the top U.S. law enforcement official, said in a speech in San Francisco unveiling the proposals.

Holder said the Justice Department would direct federal prosecutors to charge defendants in certain low-level drug cases in such a way that they would not be eligible for mandatory sentences now on the books.

Prosecutors would do this by omitting from official charging documents the amount of drugs involved in a case, lawyers with expertise in criminal law said. By doing so, prosecutors would ensure that nonviolent defendants without significant criminal history would not get long sentences.

Other proposals unveiled by Holder - such as giving federal judges the leeway to depart from mandatory minimum sentences for some drug offenses - require congressional approval, a tricky prospect at a time of partisan gridlock in Washington.

Holder labeled as an injustice the mandatory minimum sentences required under the criminal justice system in many drugs cases - condemning offenders to long prison terms even for nonviolent crimes and possession of small amounts of drugs.

“This is why I have today mandated a modification of the Justice Department’s charging policies so that certain low-level, nonviolent drug offenders who have no ties to large-scale organizations, gangs or cartels will no longer be charged with offenses that impose draconian mandatory minimum sentences,” Holder said.

Holder cited a moral imperative - as well as financial and social reasons - to re-examine policies that send so many Americans to prison.

“As the so-called war on drugs enters its fifth decade, we need to ask whether it, and the approaches that comprise it, have been truly effective,” Holder said at a conference of the American Bar Association lawyers group.

Inmates are escorted by a guard through San Quentin state prison in San Quentin, California, June 8, 2012. REUTERS/Lucy Nicholson

WORLD INCARCERATION LEADER

The United States leads the world in the percentage of its population behind bars, according to the International Centre for Prison Studies in London. Among the reasons for that are the mandatory minimum sentences and related laws enacted in the 1980s and 1990s at a time of rising crime and drug violence.

Holder said that the United States accounts for just 5 percent of the world’s population, but incarcerates almost a quarter of the world’s prisoners. He added that U.S. federal prisons are nearly 40 percent above capacity and that almost half of the inmates are serving time for drug-related crimes.

American political leaders including Republican President Ronald Reagan and Democratic President Bill Clinton championed big spending increases to target criminal gangs and drug traffickers in what has been called the “war on drugs.”

Crime has dropped in the United States since those laws were passed. Democratic President Barack Obama’s administration is betting that support for mandatory minimum laws has eroded for several reasons, including the amount of money spent by governments on housing and maintaining a huge prison population.

Another step being taken by Holder’s department would loosen the criteria for releasing inmates who have serious medical conditions or who are elderly - as long as they are nonviolent and have served significant portions of their sentences.

Holder also said he has instructed federal prosecutors nationwide to develop “specific, locally tailored guidelines” to determine if drug cases should be subject to federal charges.

It was not clear how many offenders might see shorter prison terms under the administration’s proposals. The proposals were unlikely to affect many people already imprisoned.

CONGRESSIONAL REACTION MIXED

Democratic lawmakers responded favorably to Holder’s speech, agreeing that mandatory minimum sentences had become unfair. Some Republicans said Holder went too far.

“If Attorney General Holder wants to reform our criminal justice system, he should work with Congress to do so,” U.S. House of Representatives Judiciary Committee Chairman Bob Goodlatte, a Republican from Virginia, said in a statement.

In a development that Holder called “very promising,” Republican Senators Rand Paul of Kentucky and Mike Lee of Utah - favorites of the conservative Tea Party movement - have joined leading Democrats to call for passage of legislation to enable federal judges to depart from mandatory minimum sentences for some drug offenses.

“Such legislation will ultimately save our country billions of dollars, and the president and I look forward to working with members of both parties to refine and advance these proposals,” Holder said.

For some drug offenses, U.S. law mandates that judges impose a minimum sentence. For some other offenses, judges get an advisory range from the U.S. Sentencing Commission.

Prosecutors can avoid both constraints at the outset of a criminal case when they make the crucial decisions about if and how to charge a suspect.

“By reserving the most severe penalties for serious, high-level or violent drug traffickers, we can better promote public safety, deterrence and rehabilitation, while making our expenditures smarter and more productive,” Holder said.

The Justice Department staff has been studying changes since the beginning of the year, about the time Holder agreed to stay in his job into Obama’s second, four-year term, officials said.

According to statistics kept by the International Centre for Prison Studies, 716 of every 100,000 Americans are in prison or in jail awaiting trial. That compares to 479 in Russia, 284 in Iran, 274 in Brazil, 209 in Mexico, 149 in England and Wales, 121 in China, 114 in Canada, 102 in France and 80 in Germany.

There was little indication that the administration’s proposals would affect private-sector companies that help to manage U.S. prisons. The companies specialize in housing inmates who faced immigration and customs charges, not drug charges, said Kevin McVeigh, an analyst with Macquarie Securities.