Some Washington parents are fuming at a court ruling they say makes it illegal to protect their children.

The state supreme court last week overturned the robbery conviction of a 17-year-old because it was based partly on testimony from an eavesdropping (search) parent. The ruling reinforced Washington's strict privacy act, which says that consent from both parties is required to listen in on telephone conversations — even if you suspect your child is involved in a crime or is in danger.

"That is just the most ridiculous, outrageous thing I've ever heard," says Kim Loewen, a Washington parent.

"It's a matter of protecting our children. And protecting our kids' well-being has to be more important than their privacy," seconds Virginia Day, also a parent.

Day said her eavesdropping probably saved her son's life. That's how she learned about his drug habit and other destructive behavior.

But privacy advocates fear legal eavesdropping may eventually lead to parents running roughshod over their children's rights.

"What's so magic about turning 18? All of a sudden you get rights. All of a sudden you're a full human being. What about when you're 17, 16-and-a-half? What about children who are emancipated?" wonders attorney Michael Tario (search).

The state legislature plans to introduce a bill that would "exclude" minors from the privacy act next month. But until then, parents will have to get off the line or risk getting thrown in jail for up to a year.

Click on the video box at the top of this story to watch a report by FOX News' Dan Springer.