The term "judicial activism" is often used as code for "liberal policies" but that isn't always the case. It's just that the conservative press almost never notes when the activism is in their favor. The following is from The Legacy of Judicial Activism:

It also raises the question: How can conservatives possibly square the Rehnquist Court's activist legacy with their own anti-activist rhetoric? Well, it turns out there's a trick: There are actually two different kinds of activism — conservative and liberal — and conservatives don't count decisions within their own tradition as, well, activism. In teasing this out, Keck explains that the two activist traditions have very different objectives. Conservative activists want to achieve limited government — particularly at the federal level — and tend to get there by arguing that Congress is interfering with economic or states' rights. By contrast, liberal activists want to protect the core freedoms that allow vulnerable minorities to participate in the political process. They give extra scrutiny to laws that affect those minorities, and invalidate those that they judge to put politically tinged freedoms at risk. The heyday of conservative activism was the early New Deal era, when the Court struck down one after another of FDR's legislative initiatives; Roosevelt put an end to that by threatening to pack the Court. The heyday of liberal activism was the Warren Court era of the '50s and '60s and the early Burger Court period of the '70s, which has left a legacy (including Roe v. Wade) that rankles conservatives to this day.

As to how conservatives have developed a guilt-free approach to their own brand of activism, the key to understanding this is the doctrine of originalism. The idea behind originalism is that the Court can tear a mighty swathe through acts of Congress without really engaging in activism if it is channeling the original intent of the Framers.