The new tactic of the left is to label any Supreme Court decision they disagree with as "judicial activism." It is a clever strategy, since it seeks to discredit the traditional conservative complaint about leftwing activist judges.
Let me explain why this label is incorrect. The cited case involved congress passing a law to severely restrict a core First Amendment right, political speech, in order to insulate incumbents from criticism. A side effect of the law was to muzzle groups that had been targeted by congress and to limit access to the marketplace of ideas. Of course, media corporations, who just happen to by and large be big defenders of liberal democrats, were exempted. By virtue of owning a newspaper, a corporation got special rights not enjoyed by others.
The Supreme Court correctly ruled that the law violated the First Amendment. Unlike the kind of raw judicial activism involved in the California gay marriage case, the Court didn't have to make ridiculous and highly controversial policy arguments to support its decision. It only had to focus on the actual text of the First Amendment. That is hardly judicial activism.
Judicial activism is exemplified by cases like the gay marriage case and the Arizona immigration case, where judges have to invent constitutional rights or arguments to reach a predetermined policy result. Typically, such activism is used to force policies on the country that could never have been enacted through normal democratic means. For example, such unpopular and deeply divisive policies as abortion, gay marriage, forced busing, racial quotas and affirmative action are all the result of judicial edicts. Some judges have even forced localities to raise taxes, a quitessential functionof the elected representatives, to pay for the farleft schemes they have forced on the people.
Whenever you hear a politician talk about a "living Constitution", what they actually mean is they support allowing judges to force policies on voters that the voters would never support. It has been the left's go-to technique for forcing an extreme and highly damaging agenda on the country. They wrap themselves in the legacy of the civil rights movement to legitimize it, and try to paint any popular opposition as equivalent to George Wallace standing in the schoolhouse door in defiance of court orders.