I happen to know (no time to look up the patent number now, sorry) that this is covered by a US, and EU patent. A friend of mine lost more than €30,000 to being

I happen to know (no time to look up the patent number now, sorry) that this is covered by a US, and EU patent. A friend of mine lost more than €30,000 to being sued by a firm that already holds the rights to this. I hope he figures it out before they start trolling him. My friend's “invention” also covered a product on beer-mats and serviettes that would change colour under the same circumstances, unfortunately the patent he was facing down was so broadly written that it covered basically anything that could be used to detect daterape drugs in a drink by indicating it somehow. Surely the patent could have been battled, but he wasn't in the financial position to do so.