All states must register sex offenders.

A state idea--requiring convicted sex offenders to register with local law enforcement agencies--has showed up as a mandate in the new federal crime bill.

Although 40 states already have such programs, the bill mandates the requirement with a threat to hold back 10 percent of federal grant money for fighting crime if states don't comply.

Details of the federal requirement and how states are to mesh it with privacy statutes are still up in the air. The bill, signed by President Clinton in September, specifies that people who commit sexual offenses or crimes against children be registered with local police or sheriffs' departments for 10 years, with any changes of address reported. Criminals deemed to be "sexually violent predators" are required to register for life and verify their addresses quarterly. States also are required to establish a system to notify law enforcement officials about the presence of convicted sexually violent predators who have been released from prison.

The U.S. attorney general will establish guidelines for the states, which will have three years to implement registration.

Most state laws require courts or corrections officials to inform prisoners of registration requirements just before they are released from jail. Many states require officials to obtain the anticipated new addresses of those convicted of sexual offenses and forward them to law enforcement agencies. The laws usually require offenders to report each time they move. Registration information can include statements, photographs, fingerprints, employers' addresses, Social Security numbers and aliases.

Louisiana and Washington are two of the states that make information on sex criminals' locations available to the public. Most states, however, keep the information confidential, releasing it only to law enforcement personnel.

California has the oldest registration program in the United States. Since 1947...