Fingerprints can now be used to unlock smartphones, car engines and 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. Rather than require voters to show a 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.

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 it would bring other benefits. In states where felons are not allowed to vote, 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.

Voting is a fundamental right, 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 United States 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.