THE RECORDED message at Montgomery County's Department of Permitting Services supplies callers with an array of informational tidbits, including this one: "Did you know that a sign permit is required before any exterior sign may be erected in the county?" Well, no, we didn't. But now that we do -- and we note that permits are required even for signs posted on one's house or in one's yard -- we wonder whether the county's zeal for regulation hasn't bent the Constitution beyond recognition.

Some Montgomery homeowners in the Brookdale neighborhood of Chevy Chase found out about the county's law the hard way. In protest of the pending construction of a 5,000-square-foot house that they regard as outsized and unsightly, the Brookdale residents posted signs in their yards denouncing the "McMansion for Profit in Our Neighborhood." Then, a few weeks ago, an agent of the county's Department of Permitting Services told the homeowners that they had to remove the protest signs -- unless they applied for a permit and paid a $29.70 permit fee. It was all the more galling that Permitting Services is the same agency that granted permission for the construction of the alleged McMansion in the first place.

The agency enforces regulations that require individuals to obtain a permit to display signs on private property beyond 30 days. In addition to the fee, the agency requires a drawing showing the sign's proposed location as well as a scale drawing of the sign itself before it will grant a "limited duration sign permit." The county makes the point that its enforcement is content-neutral -- political signs are treated no differently from signs announcing, say, a yard sale. And no permit is required for a sign displayed up to 30 days as long as it conforms with other requirements.

That's nice, but beside the point. Residential signs are a vital form of expression, not least for people lacking the time and money for other forms of communication. And the requirement that a permit be obtained for a small political sign posted on one's own property is tantamount to a tax levied on the expression of free speech and, as the Supreme Court put it in a ruling on a similar case, "a dramatic departure from our national heritage and constitutional tradition." As for the 30-day rule, since when was political expression constrained by a government agency armed with a calendar?

The ACLU is now on the case, and with luck it will help persuade the county to abandon its wrongheaded policy. Whatever the county's interest in preserving property values, it can hardly be used to justify such a cavalier approach to free speech.