"You can purchase an umbrella or excess liability policy which provides broader coverage, including claims against you for libel and slander, as well as higher liability limits. Generally, umbrella policies cost between $200 to $350 for $1 million of additional liability protection. "
Often times this coverage may already be included in the insurance policy. For those of you in a position to purchase these policies, I don't see a reason not to negotiate the libel protection. It sure would have helped these guys.