As you conduct research and think more about your topic, you may find that you need to adjust it somehow. The ideas listed below are not exhaustive: they're just meant to help you think about how you can change your topic (without abandoning it).
Ways to Broaden Topics
Add one or more jurisdictions. Instead of discussing only Washington law, survey statutes or cases from around the country. Instead of discussing an issue in Thailand alone, discuss the issue in Thailand, Laos, and Cambodia.
Look a little more widely.
Increase the time span you cover. Discuss how a doctrine has developed over the last several decades, not the last several years.
Define your issue more broadly. In addition to discussing the rights of subjects in academic research in psychology, think human subjects review in all academic research. In addition to discussing jurors' use of Twitter, discuss jurors' use of all social media. In addition to commenting on one case, discuss several cases that address related issues.
Add analysis from legal theorists. In addition to discussing the legal doctrine, add a discussion based on feminism, critical race theory, or law and economics.
Add a perspective from another field. In addition to discussing the legal doctrine, add perspective from social sciences, philosophy, or public health.
Ways to Narrow Topics
Limit the jurisdictions. Instead of covering all of American law, choose one, two, or a few states. Instead of covering all of East Asia, choose one country.
Break out one issue from several you have been considering and focus on that. Instead of looking at all the possible challenges to a new statute, focus on one.
Find a smaller issue within the general area of your interest. Instead of racial disparities in the criminal justice system, think of racial disparities in sentencing for misdemeanors in one jurisdiction. Instead of looking at special education across the board, focus on special education for children with learning disabilities or children who are deaf.
Narrow the time span you cover. Instead of looking at everything that's happened to a doctrine since the Industrial Revolution, can you focus on the last decade?
Ways to Differentiate Your Paper (If Others Have Written on the Topic)
Take a different position. Critique the other writers' analyses. Propose a new solution.
Extend the argument. Apply the law to new situations.
Update the material. Have later cases interpreted the statute or applied the key case? Has the legislature responded to the problem?