Many people from the UK obtain an LLM at Harvard and at other universities in the USA. There are scholarships to fund this. A UK graduate could if he or she wished apply to take a JD, but there would not usually be much point in doing so, and the costs would be high. A UK law graduate can sit the Bar exam in most States. A UK graduate with a PGDL can sit the Bar exam in California and maybe in some other states.