Some conservatives are still trying to argue that the Supreme Court is in danger of being overrun by “liberal activists.” But an article in Sunday’s New York Times, entitled “Court Under Roberts Is Most Conservative In Decades,” presented data from political scientists that pretty conclusively showed a conservative, not a liberal, ideology entrenched in the highest court.

One piece of data really stood out to me:

Four of the six most conservative justices of the 44 who have sat on the court since 1937 are serving now: Chief Justice Roberts and Justices Alito, Antonin Scalia and, most conservative of all, Clarence Thomas. (The other two were Chief Justices Burger and Rehnquist.) Justice Anthony M. Kennedy, the swing justice on the current court, is in the top 10.

That’s right: the current “swing” justice is considered one of the ten most conservative judges of the past 70 years. Centrist justices are in some ways even more important than the Court’s ideologues or even chief justices. As the Times article notes, the court’s most extreme shift to the right occurred when Justice O’Connor was replaced with the much more conservative Justice Alito:

By the end of her almost quarter-century on the court, Justice O’Connor was without question the justice who controlled the result in ideologically divided cases. “

On virtually all conceptual and empirical definitions, O’Connor is the court’s center — the median, the key, the critical and the swing justice,” Andrew D. Martin and two colleagues wrote in a study published in 2005 in The North Carolina Law Review shortly before Justice O’Connor’s retirement.

With Justice Alito joining the court’s more conservative wing, Justice Kennedy has now unambiguously taken on the role of the justice at the center of the court, and the ideological daylight between him and Justice O’Connor is a measure of the Roberts court’s shift to the right.

The statistics back up a right wing trend on the Supreme Court that has been hard to ignore. Since Alito joined the Court, it has made startling decision after startling decision, including overturning democratically enacted restrictions on corporate spending in Citizens United v FEC, and defending discrimination against women in the workplace in Ledbetter v Goodyear.

Just one justice can make the difference between democratically enacted campaign finance laws and unlimited corporate spending in elections; between employment discrimination laws that work for employees and those that work for employers; between our democracy holding corporations accountable and corporations owning our democracy.

All of which is why, when we talk about presidents and senators, we have to talk about the Court.