Many states require foreign lawyers to obtain an LLM from an American law school before practicing law in the United States. Some law schools make all of their LLM degree options open to foreign lawyers, but tack on a summer orientation course that serves as an overview of the American legal system. Many law schools choose instead to designate an entire LLM track for training foreign lawyers, and only allow graduates of overseas law schools to apply to that track. One example of this type of LLM program is the newly announced @WashULaw, an online LLM in American Law specifically tailored for foreign law students. Some law schools choose a middle-ground by offering to combine some LLM tracks with an introduction to American law, and requiring proficient knowledge of the American legal system and history as a prerequisite for others. If you are a lawyer who has earned a professional law degree outside of the United States, the first and most important step that you should take is to a) determine if your degree is already accepted in any parts of the United States, and b) confirm that any LLM programs you are considering will make you eligible to practice law in the United States.
Curricula for LLM programs aimed at introducing international students to the American legal system generally have two primary components: English proficiency, as judged by the IETLS or TOEFL, and an overview of the procedures and institutions behind the Constitution and laws of the United States.
Because some countries practice a civil law system (principles are mainly derived from written laws), while others adhere to a common law system (principles are mainly derived from judicial decisions and case precedents), adjusting to a new legal system can sometime be very difficult. Differences in city, state, and federal law in the United States mean that a mixture of the two system is in effect. Citywide and statewide legal structures are usually weighted more towards common law, while federal law predominantly follows the common law model. Even if an attorney from another country is familiar with a similar system of law, there may be important differences in the actual substance of written laws between countries, and between case histories on specific legal issues. For instance, although there were both significant similarities and differences between the American and British legal systems in the early 19th century, Britain outlawed slavery long before the American Civil War.