[sent to lawcourts re: what the Segal/Spaeth research proved]
The "research" that you speak of showed no such thing. That is only social club lore. If you put something in a headline long enough, people just repeat it.
Really, as to what can properly be said about justices and ideology by political scientists, it is only that an opinion may CONSTITUTE ideology -- not whether a brain follows it. Brains have no real choice, really, but to follow what they do. No political scientist, therefore, has come close to proving anything remarkable about jurisprudence or the ethical reality of supreme judging. Among the informed, the old debates live on as strong as before, the lead ideas not being quantitatively determined. We aren't a real science anyway; one should not expect this to be a data-driven enterprise. When people want to know what affects cancer, for example, that is predominately data driven. We wait for the latest news. But it is not so for the idea of whether justices use what you call "ideology." There is no true science here; only a language game and, I think, something fundamentally aesthetic.
If there were to be movements in this "field," therefore, they would not come from empiricists. They would come from philosophy of bias. That's the real problem. That subject has never really materialized.