Is Libelous Speech Covered Under The First Amendment?

[Fiacra]

How can it be called Free Speech if you can be sued for it?  I am taking an Ethics class and the guy in question created a web site parody about the business he works at.  Would it violate his civil right of free speech to be fired for the site?  I say no because it was unethical and the site contained libelous content.  But I cannot find the information on whether the 1st amendment covers such speech.  Any opinions or information on the subject appreciatedTz

[Julius]

libelous means it is untrue, therefore not covered under free speech rules.at will employees can be fired at any time for no reason legally