Stevens wrote the majority opinion in Kelo.
Don’t expect him to come down on the side of liberty.
He did. But, he also wrote the majority opinion in NY vs. Clinton, where O'Conner and Breyer were the only full dissenters.
Scalia was also a partial dissenter, but for reasons other than the constitutional infirmity of the line item veto.
Stevens has shown himself to be - at times - a somewhat principled jurist with respect to Art. I, Sec's 5 & 7.