In a democracy, citizens must be able to criticize their leaders. It’s a reason America’s founders put free speech in the Bill of Rights. I assumed that right is safe in the United States. So I was shocked to learn what happened in Wisconsin.

Before dawn, Deborah Jordahl was awakened by the sound of cops banging on her front door. She rushed downstairs before police used their battering ram to break the door down. The officers then said her household was under criminal investigation.

They ordered Deborah and her son Adam to step aside while they took her family’s computers, cellphones and files. They also told her, don’t talk to anyone about this investigation! If you do, you may be jailed!

They wouldn’t tell her why.

We like to think speech is free, but when government can investigate you for possibly violating countless little rules, and then order you to shut up, it censors without the public even knowing.

School buses drove by. Neighbors wondered what was going on at the Jordahl house.

Deborah’s son told me, “People came up to me at school and said, ‘Hey, what happened at your house this morning?’” He couldn’t legally answer.

No one in the family was allowed to explain that Deborah works as a political consultant, that she supported Gov. Scott Walker and limited government. Now, political incumbents who like big government were investigating her for possible violation of Wisconsin’s campaign finance rules.

Modern campaign rules are so complex no one is certain what is legal. Yet one misstep is enough to get accused not just of bad political arguments, but also of “collusion” and racketeering. Raise money for a cause you believe in and get close to politicians you favor, and you may be accused of funneling illicit money to their campaigns.

In Wisconsin, prosecutors may also impose what’s called the “John Doe” rule: Don’t tell anyone that you’re being investigated, not even your kids, your spouse and definitely not the media.

Prosecutors claim secrecy is needed to “protect privacy” of people under investigation -- if charges are dropped, no one need know that you had been accused. But in truth, says Eric O’Keefe, another limited-government activist who Wisconsin prosecutors investigated, “This is about shutting us up. That’s all it is. It is a speech suppression play.”

It’s also a way for political insiders to punish their opponents. O’Keefe is a Republican, and the lead prosecutor, Milwaukee District Attorney John Chisholm, is a Democrat, but two Republican insiders signed off on the raids, too. “I take cold comfort in having my constitutional rights trampled by both parties,” says O’Keefe.

We who support smaller government expect retaliation from incumbent politicians. But children shouldn’t be punished. Sixteen year-old Noah Johnson was home alone when cops banged on his family’s door at dawn. His parents left early that morning.

Noah was scared because he had no idea what was going on. “I’m looking around outside. There are flashlights everywhere.”

He wanted to call his parents, which sounds responsible, but, “They didn’t let me call anyone -- I was not able to call a lawyer.”

Hours later, they allowed him to leave for school, but again warned him not to tell anyone about the police!

“I was two hours late for school,” he told me, but “there’s no way you can explain it to anyone.” When his teacher asked why he was late, all he could say was, “I cannot say.”

Every John Doe suspect had to live the nightmare of knowing that the state was investigating them or their family members but that they were forbidden by the government to say what the family had done that might be forbidden by the government.

This forced silence lasted five years, until Wisconsin’s Supreme Court finally ordered the Joe Doe investigations stopped, saying prosecutors used “theories of law that do not exist.”

But political incumbents didn’t have to win convictions to achieve what I assume was one of their goals: silencing opponents during political campaigns.

 We like to think speech is free, but when government can investigate you for possibly violating countless little rules, and then order you to shut up, it censors without the public even knowing.

Campaign finance rules -- and the political incumbents and prosecutor-bullies who manipulate them -- are a major threat to our freedom.

John Stossel is the author of "No They Can't! Why Government Fails -- But Individuals Succeed" and host of "Stossel" (Fridays at 9 PM/ET), a weekly program highlighting current consumer issues with a libertarian viewpoint. Stossel also appears regularly on Fox News Channel (FNC) providing signature analysis. Click here for more information on John Stossel.