Law enforcement agencies around the country will soon be able to use their smartphones to identify subjects.

BI2's Mobile Offender Recognition and Information System (MORIS) attaches to an iPhone or other smartphone and uses biometrics from an iris, facial or fingerprint scan to determine a person's identity.

Plymouth County, Massachusetts Sheriff Joseph McDonald told Fox News that the technology was a "game changer."

But privacy advocates worry that technology may constitute a warrantless search.

"We think that there should be some rules and regulations in place that govern exactly how the police use these things so that they can be used when it's appropriate, when the police have probable cause that, you know, you have committed a crime, but that they don't start using them all over the place as sort of a generalized surveillance tool," ACLU's Jay Stanley said.

Watch this video from Fox News' Happening Now, broadcast July 27, 2011.

Watch this video on iPhone/iPad