Business owners may finally be winning the war against rats--giant inflatable rats, that is. For years, union members have inflated glowering pests--some as tall as 30 feet--in front of businesses and construction sites where nonunion labor is employed. But an administrative law judge in New York recently ruled that displaying a blow-up rat violates labor law.

Here's the explanation: Picketing is legal when members of a union are protesting safety standards or wages; so is distributing handbills. But intimidating workers, delivery people, or customers from entering a place of business where no job action has been declared is illegal. In his decision, Judge Steven Davis wrote that the rat did send "a signal to those who approached the entrance that a labor dispute was occurring"--and that the signal constituted unlawful intimidation.

Writing in support of the decision, Arthur Rosenfeld, general counsel for the National Labor Relations Board, cited the fact that the rat was featured on the TV show The Sopranos as further proof that the rat signified a formal job action. "There is a widespread understanding that a rat is a worker who refuses to join a strike or who takes a striker's place," he wrote. "Rat is a synonym for the word scab."

The union has appealed the New York decision, and meanwhile, a judge in Cleveland has ruled in a similar case that inflating a rat is a form of speech protected by the First Amendment. Some version of the rat lawsuit could eventually wind up before the Supreme Court. For now, however, the NLRB is likely to begin enforcing the ban.

So what can business owners expect next? "There is more than one way to call attention to handbillers," says Lowell Peterson, a lawyer with Meyer, Suozzi, English & Klein, the New York City firm that represented the union in the original rat case. Translation: The judge didn't say anything about inflatable skunks or cockroaches.

But that doesn't worry Bill Adams, a labor relations consultant in Fort Wright, Ky. Adams, whose clients have twice been the target of inflatable rats, says the hype is overblown. "Employees carrying picket signs," he says, "will always have more impact than some silly blow-up toy."