Is it illegal to have a countrys symbol on a business sign?

I saw a sign with the czech lion the countrys symbol on thier sign. Isn't that illegal?
No Nope. Otherwise, all the St. Patrick's stuff (especially in NYC) would have be banned. You can bet there were plenty of Irish flags surrounded by the parade and in the spectators, as well as contained by store fronts and on signs.

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Absolutely not. Why would it?

Freedom of expression. He could enjoy a picture of Osama Bin Laden..(dumb but not illegal)
It's not illegal, but near are a vareity of circumstances that could limit its use. You couldn't use a national symbol fraudulently (such as to say that the Queen shops at a store when that is not surrounded by fact the case). Also, in the U.S. you cannot trademark any part of a logo which includes the Flag- the hypothesis being you can't trademark what's not yours. That doesn't mean you can't USE the flag as your logo, you just can't trademark it.