[kevinh]

Slippery slope is famously a fallacious argument. My first exposure to it was people insisting that legalizing gay marriage would end up legalizing marriage to animals.

[jmholla]

A slippery slope is only a fallacy if there is no demonstrated history of it existing. I think we're all aware that that is not the case for surveillance laws.

[eudamoniac]

"If this observable trend continues, it will eventually reach a point that is along this trajectory" is not a fallacy.

[soulofmischief]

People's misuse of the argument doesn't weaken its appropriate application.