[mckoss]

Libel does not require that the writer knows what he is saying is false (though doing so will increase the amount of damages you can collect). You can successfully sue for libel by only showing that the statements made against you were false, and that you were damaged by them.

[dragonwriter]

That...depends. In the U.S., under federal constitutional case law, if the matter either concerns a public figure or a matter of public concern, actual malice (knowing falsity or reckless disregard for the truth) is required.

The issue here would seem likely to meet the standard for public concern.