Don't give me "smart" panties!!!

So maybe this question is completely off the wall, but since when is tracing someone's every move unbeknownst to them via their underwear, one of their most personal belongings, legal?! Is that not an invasion of privacy? Can someone please tell me how this is possible?
I feel confident that most people in the class would agree with me that this is a case of technology gone awry. When a web site selling these awful inventions (forget-me-not panties) can boast, "The technology is embedded into a piece of fabric so seamlessly she will never know it's there," something is badly wrong. I was appalled that one parent and purchaser of these devices went so far as to say, "My only comment is it would be great to have a video camera." My comment is that it would be great to have trust in children. If you have to rely on sneaky devices in order to monitor your children, you probably aren't practicing the best parenting.
This kind of technology has gone too far and has to be regulated. My questions remain: how can such devices be legal and how will they or are they being regulated?