Laws against "stalking" take effect in several states this week as part of a rapidly spreading effort.
So far this year, laws against stalking have been enacted in 19 states, a remarkable number considering that only one state had a stalking law on the books at the beginning of the year.
The pioneering state, California, passed an anti-stalking law in 1990, a year after four women in Orange County were killed despite temporary restraining orders against men who were following them.
The California bill received added impetus from cases involving Hollywood celebrities who were stalked by obsessed fans.
Donna Hunzeker, manager of the criminal justice program at the National Conference of State Legislatures in Denver, said states typically define stalking as "willful, malicious and repeated following and harassing." Most require some "credible threat" of violence against the victim.