Without even touching the harm they can do to our own supporters, this is the legal advice from the Football Supporters Federation.
NOT from the Police. NOT from the FA. NOT from the clubs. This is from the federation that represents fans – the ones who are fighting for safe standing areas, lower ticket prices, better deals for fans etc etc. And they think it’s a bad idea.
If you are a flare lighter/thrower, or know someone who is, read this – or in some cases get someone to read it to you.
And if you can’t be bothered about the consequences your actions may have on someone else, then at least think what it could mean to you personally.
http://www.fsf.org.uk/assets/Smoke-Bombs-Flares-and-Fireworks-Factsheet-for-FSF.pdf