The USPTO's General Requirements Bulletin provides detailed information about admission to the patent bar. One of the most important sections to pay attention to is the Scientific and Technical Training Requirements. Essentially, you can only apply for admission to the patent bar if you have an underlying degree in a scientific or technical field.
A J.D. is not required to take the patent exam. Anyone with a science or technical degree can take it and become a patent agent. However, patent prosecution is only handled by attorneys who pass the patent office exam.
Qualifying programs include Ph.D., master's, and bachelor's degrees in:
But if you don't have a science or engineering degree, never fear. You still might be able to become a patent practitioner. Category B of the bulletin explains that those with a bachelor's, master's, or Ph.D. in a different subject can meet the general requirements by completing coursework in physics, chemistry, biology, or other acceptable subject matter.
You may have already completed some of these credits as part of your general education requirements in undergrad. Depending on where you choose to go to law school, you might be able to fill in any gaps on the same campus. If patent practice is something you'd like to pursue, your law school's career office or your intellectual property professors can help you figure out how to fill in the gaps.