LONDON -- A question facing Britain's Parliament is this: Should a man who stood trial before his peers 20 years ago -- and was judged innocent -- be forced to stand trial again if new evidence such as DNA indicates that he committed the crime?

The answer by Parliament, if it goes along with the government of Prime Minister Tony Blair, is likely to be, yes -- try the man again.

The proposed change in the double-jeopardy law, which now prevents defendants from being tried for the same crime twice, is one element in a sweeping package proposed by Blair's government. Saying the legal system has become unbalanced at the expense of victims, Blair is calling for the most extensive changes to Britain's criminal justice system in generations.

Under the new rules, prosecutors who lose a case would be permitted under certain circumstances to simply try the defendant again. And the rules would be changed retroactively so that even people who were acquitted, say, 20 years ago could face trial again.

Another change would allow prosecutors to tell juries about previous charges a defendant has faced, whether or not he or she was convicted. As in the U.S. judicial system, that is now permitted only in rare circumstances.

"This is not a tinkering with the current legal system," said Peter North, a lawyer and principal, or president, of Jesus College at Oxford University. "These are dramatic changes, with the government trying to address what it thinks is an imbalance in favor of the accused."

Crime is a huge political issue in Britain, and Blair has made fighting it a top priority in the session of Parliament that began last month. In addition to scrapping the double-jeopardy rule and informing jurors of past charges against defendants, the proposals also include trials without a jury in serious fraud cases and increased prison time for repeat offenders.

Sexual and other violent offenders could be locked up indefinitely, but low-level criminals without lengthy records would be spared prison terms and ordered to attend rehabilitation programs, such as drug and alcohol counseling. Polls find that Britons are solidly behind the changes.

Court rules would also be tightened to make it tougher for people to wiggle out of jury duty.

Civil rights concerns

Except for the changes involving rehab and jury duty, the proposals alarm Liberty, the London-based civil rights organization. The group's most forceful objections are against allowing prosecutors to tell jurors about previous charges against a defendant. Liberty argues that it would encourage police to round up people with records for crimes they did not commit.

"If the police are investigating an armed robbery, they'll go after people who committed armed robberies, knowing that the jury is going to find out about the previous conviction -- and convict again based on that rather than any evidence," said Mark Littlewood, Liberty's director of campaigns. "The trials will not be a judging of fact, but a judging of whether a person is a good and upstanding citizen."

Robberies increased 28 percent in Britain in the 12 months ending in April, with much of the rise attributed to teens capitalizing on a burgeoning market for stolen cellular telephones. But violent crime -- which most of the proposed changes relate to -- decreased about 4 percent during the same period.

About 5 million crimes were committed in Britain during that year, but only about 20 percent resulted in charges, according to the government's Home Office. Of those charged, about 90 percent of the defendants were convicted.

"That tells you that the back end of the legal system is working reasonably well and that the real problem is the front end -- catching and charging people," Littlewood said. "Yet the government is trying to change what works."

'Taken in its whole'

Blair and Britain's Home Office, which wrote the proposed legislation, say the overhaul of the justice system is top to bottom, and that changes made in the apprehension of criminals have led to a decrease of 16 percent in armed robberies since April.

"The reform is wide-ranging, all the way through the system, from the streets to the courts," said a Home Office spokeswoman who, in keeping with practice in Britain, cannot be identified by name. "People will concentrate on single aspects of the reform, but it should be taken in its whole."

Programs to fight street crime include a $230 million effort over the past two years to buy hundreds of closed-circuit television cameras for public squares, subway platforms and the like.

Also, the government is expected to announce this month a related campaign against so-called nuisance offenses -- such as drunken and disorderly conduct -- that would allow police to issue tickets rather than haul the accused to police stations. The theory is that the ticketing will free police to investigate more serious crimes.

As for the changes to double jeopardy, the government says there are safeguards in place and that only with a judge's consent -- based on compelling and new evidence -- would anybody face two trials for the same crime.

"I think it's fair to ask: If DNA evidence can be used to free an innocent person who has had the unfortunate circumstance of being convicted, why should it not be used to convict somebody who was mistakenly found innocent?" said North, the Jesus College principal. "I think a lot of thoughtful people are sympathetic to this view."

Many people, though, see the changes as a response to the acquittal of two white men who were accused of killing a black teen-ager named Stephen Lawrence, he said.

"What is unfortunate is that a lot of people feel the changes are being proposed in direct response to the failing of one trial rather than the shortcomings of the system as a whole," North said.

He said all trials come with risks of innocent people being convicted, as shown by the release of prisoners based on DNA evidence.

But, he added, the proposals are being offered precisely because of changes in society and in technology.

"We should not be held to the belief that because these rules are old, they are necessarily good," he said. "We would also do well not to be mistaken that merely because something is new it is better."