As you've probably noticed, the law school's website has a new layout. But where is the study room reservation link? Go to the top of the page and click "Current Students" and you'll find the study room page under "Student Services." Here is the URL: http://lawweb2.law.du.edu/library/studyrooms/
Update 11/12: The URL is now http://www.law.du.edu/forms/studyrooms/