For most of the past decade, Jeremy Travis has been trudging through the back end of the nation’s criminal-justice system for answers to questions that most members of law enforcement don’t have the jurisdiction, or the political gumption, to consider.

It is a social landscape that is difficult to see and to track, and one that is of great concern, Mr. Travis argues, in a time of record-breaking prison populations and what he calls “the expanded universe of invisible punishment.”

Mr. Travis’s first book, “But They All Come Back,” is an impassioned plea on the subject of recidivism. In the book, scheduled for publication today by the Urban Institute, his main thesis is that the criminal-justice system is not working.

Mr. Travis has held a variety of high-ranking posts in law enforcement. He served as the New York Police Department’s top lawyer under three police commissioners, and later as director of the National Institute of Justice, the research arm of the Department of Justice, and of the Urban Institute, one of the nation’s premier think tanks. He is now in his first year as president of the John Jay College of Criminal Justice.

The criminal-justice system, Mr. Travis says, fails to accomplish one of its primary missions: to promote rehabilitation and “reintegration, not retribution.” In 355 pages of wonky prose more suited for reading by state legislators’ aides than by fans of potboiler crime tales, Mr. Travis documents a dramatic boom in the number of inmates around the country – most of whom are being held for drug crimes. He also explores the sky-high rates of recidivism, and the failure of state officials and lawmakers to design transition programs that work. What’s left, he argues, is an increasingly costly penal system that creates higher crime rates rather than rehabilitating prisoners.

Among state correction officials and policymakers, according to Mr. Travis, the goal of maintaining a system of fair punishment, fair sentencing, and rehabilitation for criminals has gotten lost in the transition from a boom time for prison construction to the current period of historically low crime rates.

“We now live in an era resembling the Tower of Babel,” Mr. Travis writes. “We speak no common language when we discuss the purposes of punishment.”

Scouring reams of prison statistics and clippings for a project that began with a personal assignment from Attorney General Janet Reno, Mr. Travis – then serving as director of the National Institute of Justice – said it was the sheer volume of inmates returning to prison that shocked him most.

In 2002, he says, more than 630,000 prisoners were released from state and federal prisons across America. That breaks down to 1,700 prisoners a day.

The majority of those inmates, however, don’t get far. According to statistics that Mr. Travis cites from the FBI, two-thirds of the nation’s prisoners are likely to be re-arrested for one or more serious crimes – felonies or serious misdemeanors. To Mr. Travis, the most disheartening statistic is how soon all those prisoners are typically arrested again: within three years.

Rehabilitation was once the purpose of the penal system, but now, Mr. Travis argues, it is a rarity.

And that raises a chilling question, one he argues lawmakers must consider anew: If reintegration of inmates has proved so dangerous for other citizens, should the state be held responsible for minimizing the risks?

While the language Mr. Travis uses can be detached and clinical, his experience of the prison boom is personal. When he was acting as special adviser to Police Commissioner Benjamin Ward, he remembers, he took an urgent phone call at his office on the top floor of police headquarters. This was in the mid-1980s. Mr. Ward,who also served as the city’s corrections commissioner, was on the line from Los Angeles. Mr. Ward’s tone was serious, almost grave, Mr. Travis remembers.

“He told me, ‘They have a new thing out here they’re calling ‘ice,’ and it’s going to change everything we know now forever.”

Ice later became known as crack, and crack later became the source of an urban epidemic that led to an era of high crime rates, broken families, get-tough drug laws, and mandatory sentencing requirements. Many of the inmates now being released from prisons were sent there for drug crimes they committed in the crack era. The crack epidemic has diminished, but, Mr. Travis argues, the state does little to ensure that re-integration works.

In New York, his case is a particularly hard one to sell. In the late 1970s, state lawmakers eliminated most prison transition programs, after several prisoners who had escaped from work-release programs immediately committed serious crimes. As a result, the state’s parole board was also moved from the jurisdiction of the Department of Corrections to the jurisdiction of the governor.

Looking ahead, Mr. Travis makes modest recommendations. While eliminating mandatory-sentence requirements and restoring judicial discretion could be seen as politically weak, Mr. Travis writes, correction officials could be empowered to create incentive programs that would guarantee inmates credits toward early release. Ideally, those credits could be earned both for ordinary achievements, such as good behavior, and for inmates’ willingness to be re-integrated.

Under a new incentive system, Mr. Travis argues, an inmate could receive an earlier release by conducting a job hunt while in prison, obtaining a place to live, or reuniting with family. That way, the onus of re-integration is placed on the individual. As a consequence, Mr. Travis argues, the parole board would have to relinquish certain powers – such as the right to disregard inmates’ good-faith efforts made while in prison in denying parole based on the nature of the prisoners’ crimes.

Additionally, Mr. Travis recommends “front ending” the transitional services during the time an inmate is most likely to be arrested for a crime, the first few months after release.

With “But They All Come Back,” Mr. Travis is not preparing for record-breaking hardcover sales, crowded book-signings, a movie deal, or even sweeping legislation anytime soon. There’s to be a book party this summer, and maybe there’ll be a few lectures.

“My only hope,” he said, “is that when people think about these things they have that same ‘aha!’ moment that I did,” Mr. Travis said.