If you are specializing in a specific area of law, developing your thesis in line with that area is advisable. For example, if your career path will be in criminal law, consider a thesis that delves into a controversial area of criminal law. Your thesis could delve into the history and administration of the death penalty in the United States. Draw comparisons to other nations where the death penalty is legal or illegal. Examine issues surrounding the death penalty, including whether it constitutes torture, whether it effectually deters violent crimes and the percentage of executions carried out where the individual was later demonstrated to be not guilty of the crime. You could also address disparities between the poor and affluent in obtaining quality legal representation.
The role of the Supreme Court presents numerous ideas for your thesis. For example, write about the role of the Court throughout its history, with an emphasis on how the Court has become politicized. You might also look at landmark cases that have been argued in front of the Court and the effect of the Court's subsequent rulings on American life and the culture as a whole.
If you ultimately want to defend those with little or no power, then a specific group's mistreatment might be a good subject for your thesis. For instance, the relationship that the United States has with Native American nations is unique and was marred with conflict and controversy from its inception. An in-depth look at this relationship, such as between the United States and the Navajo, would allow you to address inequities that remain unresolved.