(1) In both Canada and the United States, many people arrested for a crime never receive appropriate punishment. (2) Prosecutors often drop charges because of flaws in the arrest procedures—officers didn’t follow the rules with sufficient care or file their paperwork properly. (3) In many other cases, the charges are dismissed at preliminary hearings because of problems of evidence, such as key witnesses failing to appear. (4) Of cases surviving these barriers, many are resolved by a plea bargain. (5) That is, the charges are reduced in exchange for a plea of guilty. (6) This spares the government the expense of a trial, but it also makes punishment less severe. (7) And of those who do go to prison, very few will serve their full sentence. (8) Time off for good behavior often equals 25 percent of one’s sentence, so most will be out on parole well before their time is up. What is the main idea?