The law school application essay/personal statement provides the law schools with the opportunity to evaluate your writing and your ability to communicate an idea or theme in a clear and concise manner. It is also a great way for them to get to know you.
It is most important that your ideas be well organized and focused. Your theme choice is not limited to "Why do you want to attend law school?" but should be a topic that reflects personal values, decision making processes, significant contributions, accomplishments and/or special experiences that are not fully revealed elsewhere in your law school application.
Think of the personal statement as your opportunity to share your strengths in a positive, non-defensive way. This should not be viewed as an opportunity to explain, apologize for, or defend a negative issue or experience, such as a poor academic record or LSAT score.
In choosing a topic, take time to first analyze your personal history, evaluate experiences most relished, and determine the personal significance of learning or events in your life.
Most importantly discuss the "hows" and "whys" of your experiences. Why did you make a particular decision? How did you benefit from the choice you made? What did you value or gain from your experience? Discuss the personal significance of an event.
Keep in mind that the topic is your choice. Law schools will be interested in analyzing the content quality of your essay as well as, learning more about you. In fact, since law schools do not usually provide interviews, the essay serves as an opportunity for admissions officers to "get to know you." Think: What can I write in a couple of pages that would serve as an introduction to who I am?
Try to personalize your statement by avoiding the use of passive expressions. Instead use active language. Perfecting your grammar and spelling is a given. Vary your sentence structure and write engagingly.
Many law schools request that the length be two pages, double spaced, although some school requirements may vary. Generally, applicants can attach the same essay to each application, perhaps varying the last couple of paragraphs to address the particular issues a particular school would like you to cover.
Finally, realize that you will probably be making several drafts with many revisions and refinements. The pre-law advisor will be happy to assist you in the critique of typed drafts. Please allow 3-5 days for a thorough critique.
Berkley's Career Center has a resource on Essays: https://career.berkeley.edu/law/LawStatement.stm