It is obvious that the considerable powers granted to law enforcement to ensure public safety should be strictly controlled to avoid abuse.

For example, U.S. police officers almost always carry firearms and can use them to wound or kill criminals who are endangering others. That use of potentially lethal force is so fraught with danger that many rules exist regarding the circumstances under which officers can pull a trigger.

After any shooting, superior officers (and in some cases, civilian review boards) examine whether a shooting was justified, and the state Attorney General’s Office conducts an independent review of any use of deadly force.

Suspects must be advised of their rights if placed under arrest, which can only happen if probable cause of a link to criminal action has been established, and solid evidence must be presented before a warrant can be issued to search property.

That’s why police use of new scanning technology to investigate automobile license plates isn’t the “threat to civil liberties” that some critics seem to think it is.

Like other law enforcement technologies and procedures, scanners that record license plates to check them against databases to discover if their drivers are lawbreakers can be used for nefarious purposes.

But they have legitimate uses, and the risks of misuse can be controlled by strict conditions and review policies to be sure they don’t occur, or provide for punishment if they do happen. Right now, South Portland is the only Maine community using the scanners, but Portland will soon test one in a cruiser to consider their purchase.

State law prohibits the scanners from being used to compile lists of people attending public gatherings, including political or protest rallies, and requires that plate numbers and data collected with them be deleted within three weeks unless the information is evidence of an actual offense.

Since license plates are mandated by the state and are required to be visible in public settings, it’s not possible to make a credible claim that number collection by any means is a violation of privacy. If a harmful consequence not covered by current law results from that collection, the law can be altered to prevent it.

Plate scans are a useful law enforcement tool, and shouldn’t be banned.