Bad economic times, strong demand and higher prices have dramatically increased copper theft from vacant homes, businesses and even sewer systems. It’s a growing problem for law enforcement throughout Minnesota and other states, prompting worthwhile new efforts to make it harder for thieves to find buyers.

Democratic Sen. Amy Klobuchar and Republican Rep. Jim Ramstad, both of Minnesota, along with Republican Sen. Orrin Hatch of Utah, are introducing smart federal legislation that would require scrap metal dealers to keep better records of all transactions involving copper sales, including details about the sellers. The bill is similar to existing Minnesota law, but a federal baseline law is needed to deter thieves from stealing the metal in one state and taking it to one without restrictions.

The market price of copper has quadrupled since 2000 to more than $3 per pound. That makes stealing it very lucrative for individual criminals and more sophisticated gangs of thieves.

In Minneapolis, officers are devoting more time to chasing copper thieves — especially as the number of vacant homes has grown due to the mortgage foreclosure crisis. In St. Paul earlier this year, thieves used a tractor to tear down a building housing a welding company to steal copper. Police also have caught thieves stripping copper wire in the sewer system.

But the problem is not limited to urban areas: It’s a national and even international issue fueled by growing demand in China and other developing nations. High-profile cases in Minnesota include the 2007 theft of 11 tons of spooled copper wire in Hutchinson and a March incident in which two Pierce County men were arrested in Wisconsin trying to sell more than $19,000 worth of copper wire stolen from a railroad company.

Groups of thieves targeting foreclosed and vacant homes could make up to $1,000 by stripping just four or five homes a day. Other thieves focus on warehouses with large quantities of more expensive industrial copper wiring.

The thefts can pose a greater threat to public safety. Recently an unoccupied Minneapolis apartment complex exploded, and the building next door was damaged, because of a natural gas leak caused by stolen copper pipes.

A national group of recyclers opposes the proposed legislation, arguing that it would discourage recycling. They say the focus should be on prevention and punishment.

That argument doesn’t hold up. The legislation would help legitimate dealers discourage theft and would not put an undue burden on law-abiding, responsible scrap metal buyers. Dealers would simply have to maintain sales records for a minimum of one year and make them available to police. All transactions of more than $250 would be done by check instead of cash, and hefty fines would be imposed if dealers failed to comply.

Making the precious metal more difficult to sell is a promising strategy. If a product is harder to fence, it’ll be less valuable to thieves. Placing reasonable requirements on buyers is a sensible step that would help police deal with a problem that’s diverting valuable resources and threatening public safety.