Apply to a university that offers an established dual degree program in law and your discipline of choice.
Note your interest in a dual degree program on your application. Applicants must meet the requirements and be accepted within both the law school and the PhD program. Many PhD programs require a Master's degree before pursuing a Doctorate.
Organize a time frame and plan of study with an academic counselor or professor on the best way to balance classes and complete a dissertation. This is a requirement in some universities. Some colleges require that students submit a plan of study to a faculty member following admittance.
Complete coursework in both the law school and the PhD program. Universities have different requirements for how graduate and law courses can be completed. At some universities, students complete all law courses before completing PhD courses. Others allow the students to choose which year they want to devote to which degree. During upper level terms students can cross-register for a limited number of courses that will earn credits toward the both degrees.
Complete the general comprehensive exam in the area of the PhD study. There are no comprehensive exams for a JD.
Complete a dissertation in the area of PhD study and present it to a dissertation committee. Upon acceptance of the dissertation, students will graduate with both a JD and PhD.