According to http://stackoverflow.com/questions/8045235/infopath-2010-validate-i-agree-checkbox-before-submitting you can set a checkbox to "required" and it will validate that they have to check it before submitting the form.

But when I set this up, it does not require it to be checked. Is there something I'm missing, or is that first sentence in the answer just inaccurate?

[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/TSCo6.png