The law is often stupid.

For the longest time, ( maybe still, i don't know ) LED flashers were illegal in the UK, not so much because they flashed, as such, but because they didn't meet the British Standard for bicycle lights. The critical piece? "An incandescent bulb" as part of the requirement. Technology obsoletes law, again.

Never heard of anyone who got a ticket for it, but there's always one "Shiny Buttons" constable out there.

http://www.express.co.uk/posts/view/...r-in-the-clear