The most important accreditation for any law school is issued by the American Bar Association. If you attend law school at an institution that is not accredited by the ABA, in most cases, you will not be eligible to sit for the bar exam in your state. Most law schools will advertise accreditation by saying that it is "ABA-Approved." Study of criminal justice should only be done at ABA-Approved schools. The large exception to this rule is in California, where schools do not need to be affiliated with the ABA, because the California Bar Association has much different regulations governing education and bar eligibility.
There are a number of independent bodies that rank law schools according to a number of criteria, including the quality of the education offered, and the typical quality of employment that will be obtained upon graduation. Students can use these rankings to help them decide to which schools they should apply. The "U.S. News & World Report" rankings are used by many students, but the top of their rankings are consistently dominated by the same schools such as Yale and Harvard. These rankings tend to be generalized, so more specific investigation into the quality of the criminal justice education offered by those schools is warranted.
Most law students take classes that are similar during their first year. Then, they move on to taking classes that fall into their specialty. A criminal justice law program will offer classes in basic criminal law and a number of electives in specialized areas relating to this particular type of law practice. Classes can focus on prosecution, defenses, evidence, sentencing, procedure, federal criminal law and more.
In most law schools, there are a number of activities outside of the regular classwork that is is important or required for students to complete. Harvard has a specific criminal justice track and has a number of out-of-class activities for students to participate in. Clinical programs and internships are viewed as an integral part of the legal education at most schools. Harvard requires students to complete at least 40 hours in legal practical work, and also has pro bono requirements.