There's a saying that one man's tragedy is another man's treasure.
And here's the proof: so far the French authorities have received 50 requests to register "Je suis Charlie" as a trademark since the murders at the French magazine Charlie Hebdo in January.
The French trademark office has rejected all of them, because the term is already widely used, does not have "distinctive characte", and that a trademark would be against "accepted principles of morality".
But other applications have also been filed in Benelux, Australia and America, although none in the UK.
Cleland Thom is author of Internet law for journalists