Twitter has started warning developers that it won't let them use public programming kits or Gnip data for surveillance reasons, whether the clients are law enforcement or anyone else, Engadget reports.

Just because many tweets are public doesn't mean it's acceptable to harvest them, Twitter says. To that end, it's promising "expanded" efforts to crack down on developers who use the data for surveillance reasons.

To Twitter, the reasoning is simple: the company is devoted to "social justice," and that's not possible when officials are using these public data sets to track protesters, scoop up people's names and otherwise curb freedom of expression.

The policy and resulting crackdown isn't going to stop authorities from collecting information through other means, whether it's old-fashioned searching or some other forms. However, it'll at least make the process harder, Engadget says. Agencies will have to really want that information to get it, and can't just gather it en masse with a simple program.