I've been repeating this ("a law") since the Snowden leaks days. I was so sure. But I tried to look up my reference for it (it was Wired) and I'm just not finding it and indeed I'm finding government memos (https://web.archive.org/web/20160112232215if_/http://www.wir...) that show it isn't true.

I'm sorry. It is not a law. I am wrong. Thank you for the correction and preventing me from continuing to repeat this embarrassing falsehood.

That said, they do still collect and use this data and turning off GPS doesn't do anything.