Comment by Bartweiss

Probably Griswold v. Connecticut, which established the derived right to privacy. Justice Douglas cited the Third Amendment (among others) as implying the right to keep one's home free from agents of the state.

That said, this pretty obviously isn't a clear Third Amendment violation. There's virtually no caselaw around the 3rd, and what there is has held it pretty narrowly. The only successful Third Amendment defense I know of was Engblom v. Carey, which was about evicting prison guards to give their housing to National Guard troops.

So - I think they meant "right to privacy", but the 3rd is one of the smallest and least-cited components of that right.