Why do some employers ask you to sign something giving them permission to check your references?

• accept credit
• sign frames
• permission marketing

I went to an interview recently and I was asked to sign a paper giving them permission to check my references. Stupid me was so trusting I never even read the darn paper I just signed it believing what the lady said the form was for "giving her permission to check my references" the interesting thing is they ask you for references when u submit ur application. So wouldn't that be all they needed? Im freaking out because I have no idea what the paper said shoud I even panick? I mean what else coukd it have said? I just cant believe I signed without reading I NEVER do that I think I was just so happy to get an interview I didnt think...please help any info greatly appreciated.

Why do some employers ask you to sign something giving them permission to check your references?