According to the Ventura County Star, they are suing to block an ordinance that forbids sex offenders from doing just that. The lawsuit claims the measure violates the 1st and 14th amendments of the U.S. Constitution.
Among other things, the ordinance requires sex offenders to post signs on their front doors saying "no candy or treats at this residence."
The Simi Valley city attorney calls the lawsuit groundless.
This story is from our sister station KABC-TV in Los Angeles, CA.