In the US, you cannot enter law school until you have completed a bachelors degree (4 year degree). Law school is then a 3 year degree after this-so a total of 7 years. You could absolutely get an undergraduate degree in economics (I would suggest business economics) and then apply to law school your senior year. A bachelors in Business is often more difficult than other degrees, and law schools look favorably on students that study business-it shows they are willing to work hard and challenege themselves. These students are often accepted to the law school of their choice.
Good luck!