State Sen. Patricia Vance had never heard of "upskirting" or "downblousing" until a constituent called to say it had happened to her.

A man in a Cumberland County mall's food court had snapped a picture up the woman's skirt with a cell phone camera. His reward: a photo of the woman's butocks and thong underwear, and a trip to jail.

"I truly didn't know what it meant. Evidently, in some areas of the state -- [colleagues] told me specifically in Philadelphia -- this happens a lot," Ms. Vance, R-Cumberland, said. "I guess there's more perverts out there than I thought."

As her case headed to trial, the woman called on Ms. Vance to amend what some call a loophole in the law -- one that led a judge in August to find the photographer not guilty of invasion of privacy.

The senator threw her weight behind a bill already in the state House and last week, Gov. Ed Rendell signed it into law.

The new act makes it illegal to take pictures of someone's "intimate parts" without their knowledge or approval in a place where there is a reasonable expectation of privacy. It expands the language of the law to include electronic devices like camera phones.

"I think it's a good piece of legislation," said state Fraternal Order of Police President Mark Koch, whose organization endorsed the law.

Pennsylvania joined more than a dozen other states in passing legislation to criminalize upskirting and downblousing. Both the Pennsylvania District Attorneys Association and the Pennsylvania Coalition Against Rape supported it.

"The law has to keep pace with technology," said Diane Moyer, the coalition's legal director.

"Can you imagine your mother going to the mall and having some perpetrator take a cell phone and violate her private space and later see it on the Internet?" Ms. Moyer said. "It's ghastly to contemplate."

Although the law was well received by Legislature -- it passed the House and Senate unanimously -- it added an extra hurdle for prosecutors. They have to prove that an invasion of privacy occurred for the "purpose of arousing or gratifying the sexual desire of any person."

That, said attorney John Abom, provides suspects with a possible defense because the burden would be on prosecutors to prove intent.

Mr. Abom knows about defending people accused of upskirting and downblousing. He successfully defended the man in the mall case.

He argued, and Cumberland County Common Pleas Judge Edgar B. Bayley agreed, that the law on the books at the time of the case did not make his client's actions illegal.

Judge Bayley ruled that a woman would not have an expectation of privacy under her skirt because of the way state law was written. He explained that the invasion of privacy statute defined a place where someone would expect privacy as "a location where a reasonable person would believe that he could disrobe in privacy without being concerned that his undressing was being viewed, photographed or filmed by another."

"That location," the judge wrote, "is conceptual, not spatial. It simply is not under a woman's skirt. Enacted in 1998, this statute was not written in anticipation of the cellular telephone/camera."

The new law, however, addresses that distinction. It also tries to be forward-looking by being open-ended enough to include advances in technology, said Joyce Frigm, a House staffer who worked on the bill for its sponsor, state Rep. Russell Fairchild, R-Union.

Ms. Frigm said an upskirting bill had been introduced by a different legislator prior to the Cumberland County case, but it died when the legislative session expired.

She is aware of several instances of upskirting and downblousing, having received correspondence from a Lancaster County police department and assistant district attorney about an incident there.

However, there is no research showing a nationwide epidemic.

"There's no Downblousers Anonymous I became aware of," Mr. Abom said.

Police and legislators are aware that the law does not provide officers with any ammunition to investigate or prevent upskirting or downblousing. But making it illegal, they say, can only help.

"It's a tool for law enforcement and it's a tool for the courts," Ms. Frigm said.