Because they operate outside of the users privacy controls in the browser. You are accessing the users data without permission, a violation of Electronic Commun

Because they operate outside of the users privacy controls in the browser. You are accessing the users data without permission, a violation of Electronic Communications Privacy Act. That is a simple summary, you can find more in the complain. I just uploaded a copy of it here: https://docs.google.com/file/d/0Bx25s45t4-d_bDBDRjFDOUlFOUU/edit?usp=sharing https://docs.google.com/file/d/0Bx25s45t4-d_bDBDRjFDOUlFOUU/... KissMetrics settled and paid $500,000. They also let users opt out and were better about disclosing the practice on their website.