If a radio station airs a conservative commentator’s critique of a liberal author and does not allow the author an opportunity to appear on air, it could have violated the

If a radio station does not allow the liberal author an opportunity to appear on air due to a conservative commentator’s critique, then it could violated the right of rebuttal.

This is a Federal Communications Commission regulation for giving every person the right to have the opportunity to respond to personal attacks made on a radio or television broadcast.  This way, an equal opportunity may be serve to all individuals and a freedom of free speech is exercised.