Environmental activists come in all temperaments, but the ones who carry their philosophy to an extreme have earned a pithy nickname at the Sport Utility Vehicle Owners of America headquarters in Washington, D.C.: "eco-terrorists." Experts there are well acquainted with them. Indeed, they say they can plot the routes these activists will take after they leave various "green" conclaves.

The first attack, which will take place within 200 miles of the meeting, will feature vandalism on SUVs parked at an auto dealership. Then, about a day's drive away, another attack will occur in which nasty messages, such as "Fat, Lazy American," are spray-painted on SUVs. Then, perhaps they'll dip south and set a home on fire, as they did in San Diego and Indiana last year, or vandalize a store, set off homemade bombs or commit some other crime.

After about a week, the attacks will fizzle. The eco-terrorists will have returned home. They don't do this to their own neighborhoods.

SUVOA officials are right to consider these vandals criminals. And SUV owners are right to call on government to find those responsible and get them off the streets.

But they're wrong to call for federal legislation to make vandalizing SUVs a federal crime with federal penalties. Local and state laws already make vandalizing vehicles or setting off bombs illegal. Local and state laws forbid trespass onto private property or damaging someone else's belongings. And local and state laws are at least as effective -- if not more so -- than federal statutes at preventing crime.

Ask those who worked to make carjacking a federal crime. Moving jurisdiction over this crime to federal hands didn't impress the nation's carjackers. The law did nothing to cut the incidence of carjacking or improve the chances that perpetrators would be caught.

Yet after SUVs made at a factory in his district were vandalized, Rep. Chris Chocola, R-Ind., introduced legislation that would make ecoterrorism a federal crime. It may seem a relatively inexpensive and harmless solution to a growing problem. But it may, in some circumstances, bring about less enforcement of laws against vandalizing SUVs and less of what the Sport Utility Vehicle Owners of America and others say they want -- protection for SUV owners.

Why? When the United States began, there were three federal crimes: counterfeiting, treason and piracy. The reasons these crimes had to be federalized are obvious -- counterfeiting dilutes the value of all our money; treason endangers the entire nation; and pirates couldn't be permitted to flee from one state to another, or onto the high seas, to avoid prosecution.

Today, the Congressional Research Service can't calculate how many federal crimes there are. The American Bar Association says there are more than 3,000 separate criminal offenses and 40 percent of those were passed in the last 30 years. There are at least 10,000 offenses in all, counting regulations that carry criminal penalties. It's likely that more are on the way, given that courts exercise no restraint on what should be a federal criminal law. And, as a variety of legal experts have noted, no limits on federal criminal law means no limits on prosecutorial discretion.

Why would this be a problem? Take a prosecutor who has before him a suspect accused of attempting to build a dirty bomb for al Qaeda, a public figure accused of insider trading on the stock market, the kingpin of an area cocaine ring, and a scrubby-faced pair of "environmentalists" in for spray-painting messages on SUVs. The SUV owners will be lucky if the prosecutor gives them the time of day.

Conversely, local law enforcement authorities have a responsibility to the taxpayers -- personal and corporate -- who pay their salaries. They are the first line of defense between eco-terrorists and their own communities. Wouldn't attacks on SUVs be a higher priority for them?

Besides, if the law were enforced, it would waste limited federal resources and provide a ready excuse if local law enforcement failed in its primary responsibility.

No one can blame SUVOA for wanting the "biggest" solution to its problem. And no one can deny that groups such as the Earth Liberation Front have caused millions of dollars of damage to vehicles and businesses nationwide.

But a new federal law -- soon to be lost among the thousands of other federal laws and prosecuted indifferently by overwhelmed U.S. attorneys with bigger fish to fry -- is not the best solution.

Paul Rosenzweig is a senior legal research fellow in the Center for Legal and Judicial Studies at The Heritage Foundation and adjunct professor of law at George Mason University. Trent England is a Legal Policy Analyst for The Heritage Foundation.