What it is:
"1. Definition of Trade Libel
"Trade libel is the intentional disparagement of the quality of property. "Unlike classic defamation, [the defamatory statements] are not directed at the plaintiff[base ']s personal reputation, but rather at the goods a plaintiff sells or the character of his or her business, as such." Guess v. Superior Court , 176 Cal.App.3d 473, 479 (1985). The disparagement must result in pecuniary damage to the plaintiff. The disparagement may be in the form of a false statement of fact or opinion. (see 5 Witkin Sum. Cal. Law Torts §573, citing Rest.2d, Torts §§626)."
Law against it (states may have their own in addition):
The Lanham Act makes it illegal:
"Any person who ... in connection with any goods or services ... uses in commerce any ... false or misleading description of fact, which ... in commercial advertising or promotion, misrepresents the nature, characteristics, or qualities ... of his or her or another person's goods, services or commercial activities ... shall be liable in a civil action by any person who believes that he or she is likely to be damaged by such act."
A few more resources.
Relief you can request would include an injunction to stop whatever disparagement is occuring, very much what the folks in Germany got.