(TNS) Fingerprints can now be used to unlock smartphones, car engines, even guns. Why not ballots, too?

A New Mexico legislator has just proposed that his state’s election officials study the feasibility of a biometric voter identification system. The idea is simple enough: Rather than require voters to show a particular type of document that not everyone possesses, the law could require election officials to collect a piece of information — a finger image or an eye scan — from all voters, which would confirm their identity at the polls.

The political appeal of the idea is clear: Republicans would have the ID laws they claim are needed to protect against voter fraud. And Democrats would have a system that doesn’t disproportionately hurt minorities and the poor. Both parties could declare victory in the war over voter ID and move on.

To be sure, it would be an expensive way to prevent a crime that is all but nonexistent: voter impersonation. If that were the only rationale, it would be hard to justify the cost.

But in addition to freeing voters from photo ID requirements, it would bring other benefits. In states where felons are not allowed to vote, for example, biometric images could be cross-checked with prison records to identify anyone who is illegally registered. A biometric ID would also allow election officials to make their notoriously unreliable voter rolls more accurate.

Training poll workers to use the technology would be a challenge. But it would not be insurmountable, as other countries are showing. From Brazil to Yemen to the Philippines, biometric voting is spreading. Africa, where voter integrity has long been a problem, has been an early adopter.

Elections that use biometrics haven’t always gone smoothly. When voters have trouble using the finger scanners, as happened in Brazil’s recent presidential election, long lines of frustrated voters can result. As the technology improves, however, biometric voting systems will become more efficient — and increasingly standard around the world.

In the U.S., new voters could submit their fingerprints as part of the registration process, and all other voters could do so at the polls. This would allow a state to gradually phase out its ID requirements. Privacy protections would of course be needed to prevent biometrics from being encrypted with other personal data. And safeguards would be necessary to ensure that any technological problems do not disenfranchise voters.

Voting is a fundamental right, and it would be nice if government were as interested in registering eligible Americans to vote as it is in stopping the rare impersonator. But a functioning democracy rests not only on access to the ballot box but also on public confidence in the integrity of elections. And there is overwhelming public support in the U.S. for voter ID laws. Those who wish to avoid them need to start offering a better alternative. A legislator in New Mexico may have just put his finger on it.

©2015 Bloomberg News