There isn't really one specific major that is most helpful to becoming a lawyer. In fact, law schools don't require a specific major. This is a good thing because it allows you the opportunity to major in what you're actually interested in versus what is "required." There are some majors that are common among people who go to law school. These majors include political science, philosophy & english. Although these are popular majors among law students, this does not mean law schools "prefer" these majors. In fact, law schools like to admit a class of students with different majors and experiences. Some colleges also offer a pre-law minor as well as mock trial or debate programs.
Since every field has an area of law that relates or applies, you can likely find a major that is associated with that industry. However, there are some areas of law that might not directly relate to any major. For example, employment law, family law or insurance defense don't really relate to any specific type of college major.