Both Columbia and Harvard's deferral programs require 2 academic letters of recommendation and will accept a maximum of 3 letters of recommendation. If you do submit a 3rd letter, it should be a non-academic/professional letter of recommendation.
Regular Law School Application Cycle
Most law schools require 1-2 letters of recommendation. Some law schools will also have caps on the maximum number of letters of recommendation that will accept. Even though most law schools will accept a combination of academic and non-academic/professional letters of recommendation, there is a strong overall preference for academic letters. If you are applying to law school as a college senior, you most certainly want to make sure that you have academic letters of recommendation. If you are applying after graduating, academic letters will be less important the longer you have been out of college. If you are applying within 1-2 years after graduating from college, it is best to still secure academic letters. If you are applying 3 or more years after graduating, many law schools will be willing to accept non-academic/professional letters of recommendation in the place of academic ones.
For details on best practices for Letters of Recommendation, click on the link below.