Cosby trial puts U.S. states' sex-crime prosecution laws in focus

The opening of Bill Cosby's sex assault trial on Monday highlights a quirk of the U.S. legal system, in which standards vary widely from state to state on how much time prosecutors have to file criminal charges after an alleged assault.

State statutes of limitations on prosecuting sex assault vary widely - from California, which has no limits, to New York, where prosecutors must bring charges within five years for many attacks on adults.

Advocates for sex-assault victims say feelings of shame after an attack can delay people from reporting alleged assaults, particularly if they are victimized as children.

The clergy sex-abuse scandal in the Roman Catholic church, which burst onto the international stage in 2002, prompted calls to reform laws on prosecuting child sex abuse. The Cosby case, in which only one of dozens of alleged assaults is subject to prosecution, has prompted a new focus on the limitations of prosecuting cases involving adults.

"I had never been asked about adult rape statutes of limitations until the Cosby cases," said Marci Hamilton, CEO of Child USA, who has researched child sexual abuse and legal limitations for more than 15 years. "It literally kick-started the conversation."

Here is a look at the complicated rules of criminally prosecuting sex crimes:

* California in December passed a law to eliminate time restrictions for prosecuting rape and many other sexual offenses, against adults. Previously, the state had a 10-year statute of limitation for assaults on adults and gave prosecutors until the victim turned 40 to prosecute abuse suffered as a child.

* About 10 states, including Delaware, Wyoming and South Carolina, have eliminated the statutes of limitations for felony sex crimes against adults, according to the Rape, Abuse & Incest National Network, a national anti-sexual violence organization.

* Thirty-seven states, including Arizona and Virginia, have eliminated time limits on prosecuting child rape, according to Child USA.

* New York has some of the shortest prosecution deadlines for adults. Many sex crimes other than first-degree rape, including when a person is unable to give consent to sex because they were intoxicated, must be charged within five years if the victim is an adult. The state allows more time if the victim was a child or was drugged.