When President Bush II left the White House in 2009, the 13 U.S. courts of appeal were firmly under Republican appointees’ control. Ten appeals courts had majority GOP judges, two were evenly split and only one had a majority of Democrats.

President Obama’s 49 appeals court appointees have dramatically altered the landscape. As of the Senate’s recess on May 23, nine of those courts had majority Democratic appointees and four had Republican majorities. (There are 10 vacancies in the circuit courts. One Obama nominee is awaiting a Senate vote and three nominees pending in the Senate Judiciary Committee.)

The change, much feared by Republicans, is not necessarily shocking. But the transformation, in just 5 1/2 years, said University of Pittsburgh law professor Arthur D. Hellman, an authority on the federal circuit courts, marks  “a huge shift in a very short period of time.”

And it means that Democratic appointed judges “have the ability to control every important case if they wish to” in those nine circuits, he said.

The reason that’s important is because those courts are often the courts of last resort, he said, since the Supreme Court rules only in about 75 cases a year and has not weighed in many areas, including issues of import to business or the First Amendment rights of student internet expression. The appeals courts, in contrast, issue thousands of opinions a year.

Until the high court speaks, “the law that counts is the law of the circuit,” he said.