It was a very unusual criminal case. Even the biggest criminal cases in North Dakota are over in less than a week. The length of the O.J. criminal case was probably caused by the judge, the lawyers, and the number of witnesses. The State must prove a criminal case beyond a reasonable doubt. When a jury finds someone not guilty, it is not saying the person is innocent , but that the State did not prove the person guilty beyond a reasonable doubt.
Appeals take much less time today than a number of years ago, but they still take time.
A time is set for the attorneys to argue their case in front of the Supreme Court. The Justices then write opinions, and discuss back and forth, until a decision is reached. Some cases take longer than others. He's argued a number of cases before the Supreme Court, and has a good win-loss record. No trials take place in the Supreme Court.