By Amy Feldman

By Amy E. Feldman

PHILADELPHIA (CBS) – Once and for all: Is it illegal to flash other drivers to warn them that there’s a speed trap?

Way back in November of 2012, Missouri resident Michael Elli wanted to let others on the road know to slow down because they were about to drive into a speed trap so he did what many kind-hearted souls do: he flashed his headlights as a warning. Police flashed him a ticket of his very own for obstruction of justice, saying he was interfering with a police investigation.

Prosecutors eventually dropped the case but, in 2013, Mr. Elli filed a lawsuit against the city because he says that the city retaliates against drivers who exercise their right to free speech – and that the government is trying to prevent it because it doesn’t like the message.

In 2014, a federal judge ruled that flashing one’s headlights is a form of speech, protected by the First Amendment. Which is why it’s hard to believe that it took until last month for a different city in the same state of Missouri to officially change its ordinance so that flashing headlights isn’t a ticketable offense.

So, it’s your right to flash your headlights to warn others of the peril ahead. Of course if you really want to help other drivers, you might want to remind them of the perils of speeding, not just to avoid a speed trap.