The juris doctor, or J.D., is a prerequisite to most bar admission exams in the United States of America.
Initially, American law schools, such as The College of William and Mary, and that of Harvard University, issued traditional LL.B. degrees to their graduating students.
In the mid-1800s, some American educators sought to emulate law schools in Europe and increase the educational curriculum for law school students so that they would be roughly equivalent to doctorate students of the epoch.
To distinguish the doctorate-level degree from the LL.B., the novel term juris doctor or J.D. was created.
Over time, all American universities adopted the nomenclature and those issuing LL.B. adjusted their curriculum in keeping with the J.D. initiative.
The term creates considerable confusion as distinct from the doctorate-level doctor of law or LL.D. degree. The attempt to solidify the basic law degree to a doctorate level failed and even American law schools have had to re-invent first a master's degree in law (LL.M.) and then a Ph.d. or doctorate-level law degree program with the awkward name of Doctor of Juridical Science or J.S.D.