The first category of law schools requiring a Dean's Certification is those requiring certificates from all applicants. There are only seven American Bar Association (ABA) accredited schools that require a dean's certification with the initial application form; they include Stanford University, Howard University and Bringham Young University. These schools represent the top, middle, and bottom tiers of the U.S. News law school rankings, so there is no meaningful correlation between a school's up-front requirement of Dean's Certification requirement and that school's ranking or prestige.
Some schools request a Dean's Certification from applicants whose forms raise questions about their ethical conduct. Generally, these schools will request Dean's Certification from applicants who answer "yes" to questions about criminal and disciplinary history. This category includes schools such as Columbia University, Cornell University and Duke University. Of the seven schools in this category, four are in the highest tier of the U.S. News Law School rankings.
Some law schools require a Dean's Certification when admitted applicants pay their seat reservation deposit. This is the largest category of schools requiring a Dean's Certification, and includes members such as Boston University, Georgetown University and Stetson University. There is some overlap between this category and the conditional category, because some schools require certification with deposit depending on conditions.
In general, the more highly ranked a law school is, the more likely it is to require a Dean's Certification. Five of the top ten ranked law schools of 2010 (according to U.S. News and World Report) require a Dean's Certification, but only 20 or so schools out of the several hundred ABA accredited law schools require the same. Therefore 25% of Dean's Certification-requiring law schools are in the top 10 most highly ranked law schools in the country.