I think that in the registration legalese:

[quote]You agree not to post any abusive, obscene, vulgar, [b]slanderous[/b], hateful, threatening, sexually-orientated or any other material that may violate any laws be it of your country[/quote]

we should use "[url=https://www.dictionary.com/browse/libel]libel[/url]" instead of "[url=https://www.dictionary.com/browse/slander]slander[/url]."