(Pedantic nitpicking) You mean anti-SLAPP laws.
For others' curiosity: A SLAPP is Strategic lawsuit against public participation, a strategy for plaintiffs to silence opponents by way of burdening them with an onslaught of lawsuits and hoping they are scared away by potential legal costs of mounting a defense thereby resulting in them just giving up. The potential for this strategy to have chilling effects gave rise to anti-SLAPP laws.