The ruling upholds the felony guilty plea of Mark Jahnke, who videotaped his girlfriend while she was naked and while they were having sex. He argued in his appeal that because the woman agreed to be naked around him, she had no reasonable expectation of privacy.

The state Department of Justice argued that shared intimacy does not give a person the right to film another unknowingly.

Jahnke's attorney, Michael Herbert of Madison, argued that the court had found in a previous case that a reasonable expectation of privacy existed when a nude person reasonably believed he or she was "secluded from the presence of others."

Prosecutors argued the video voyeur law would make no sense under that interpretation. The appeals court agreed, saying the definition in the previous case was not intended to cover all circumstances.

Judge Charles Dykman, the dissenter in the 2-1 decision, said the 2001 law does not specifically prohibit what Jahnke did.

Attorney General J.B. Van Hollen praised the ruling.

"Wisconsin's citizens enjoy a reasonable expectation of privacy not to be secretly videotaped while in the nude, and Wisconsin's criminal law has been correctly interpreted to protect that expectation," he said.