You should ask your recommenders which titles they prefer. If you google their curriculum vitae or their bio in the university website, you should be able to obtain information about their title as well as their phone number.
@sx23 no but I feel dumb for sending them an email. They clearly say on their website that they waive the fee for any application received between 9/1 and 12/1 http://www.law.northwestern.edu/admissions/faq/faqjd.html