Three high school students in Fairfax County, Virginia, made cellphone videos of drunken sex acts with fellow teens and shared them among themselves. Now they are going on trial, facing a charge usually reserved for adult predators: child pornography.

The case is one of a number in Virginia where teens caught "sexting" have been charged with a felony that can carry a sentence of 20 years in prison and could require registry as a sex offender.

In Virginia, Maryland and many other states, the law has not caught up with the combustible mix of teens, technology and sex that has made sexting an issue. Prosecutors must rely on a patchwork of laws that were created before the rise of smartphones to handle such cases.