Hackers today are testing mobile devices ever more strenuously, but the work often stands on shaky legal ground, according to Jennifer Granick, an attorney for ZwillGen, a law firm that specializes in legal issues related to the Internet. Granick was formerly civil liberties director for the Electronic Frontier Foundation.

Presenting at Black Hat, a computer security conference in Las Vegas, Granick outlined the tricky legal landscape that faces researchers trying to work in mobile. While historically, companies have often been reluctant to open their arms to hackers, mobile devices introduce new challenges, such as having to deal with tangled FCC regulations, and laws that aren’t designed for modern devices.

For example, Granick explained, techniques such as jailbreaking iPhones to run non-Apple approved software are governed under U.S. copyright law. The U.S. Copyright Office reviews its rules every three years, and did add exemptions to allow jailbreaking. However, since the iPad didn’t exist the last time this review happened, jailbreaking these devices exists in a legal limbo.

Just to work on devices often requires taking some legal risk. Companies such as Apple lock down mobile devices and software through restrictive developers’ agreements and end-user license agreements, as well as with technical protections that are backed by law.

One particularly tricky area is location-based services. In many cases, Granick said, how communications are classified can determine how severe the legal risk connected with hacking them becomes. Accessing communications in a way that could be considered wiretapping comes with strict legal penalties, but accessing stored communications is sometimes treated differently. Under some interpretations, Granick said, there might be reason to classify communications between users and companies such as Foursquare so that intercepting them would be considered wiretapping.

Considering the fierce debates already going on around the info that passes through mobile devices, Granick’s talk illustrated the legal difficulties of pinning down exactly what goes on.