LOS ANGELES — LAST week the F.B.I., the Drug Enforcement Administration and other federal law enforcement agencies instituted a policy of recording interrogations of criminal suspects held in custody. Only a minority of states and local governments have a similar requirement, but the new rule, which applies to nearly every federal interrogation, will most likely spur more jurisdictions to follow suit. It’s not far-fetched to think that such recordings may soon become standard police practice nationwide.

Supporters of the practice present recordings as a solution for a host of problems, from police misconduct to false confessions. But while there are lots of good reasons to require them, they are hardly a panacea; in fact, the very same qualities that make them useful — their seeming vividness and objectivity — also risk making them misleading, and possibly even an inadvertent tool for injustice.

Support for electronic recording has been accelerating in recent years, and its backers now come from all sides of the criminal-justice process. Though some in law enforcement remain critical of the idea, firsthand experience with recording tends to turn law enforcers into supporters — it eliminates uncertainty about police conduct and lets investigators focus on the interrogation rather than taking detailed notes.

Likewise, criminal prosecutors find that when a defendant confesses or provides incriminating information, the video offers vivid and powerful evidence. At the same time, it aids defendants because the very presence of the camera is likely to reduce the use of coercive or unfair tactics in interrogation, and documents illegitimate behavior if and when it does occur. And a recording provides judges and juries with information about what took place in a more objective form.