Here is how another TLS post put it:
For each class, DS = 5, H = 4, P = 3, LP = 2, and F = 0. Calculate a GPA by calculating a weighted average of your grades for the year (weighted by the number of credits). Then average each of the three years of law school.
Thus, imagine a student with 1 DS and 4 Hs in regular 4-credit 1L classes and all Ps in the other 5 classes (including in both semesters of LRW and a 4-credit elective). That comes out to (from best grade to worst, by number of credits): [(4 * 5) + (4 * 4 * 4) + (3 * 4 * 3) + (2 * 2 * 3) ] / 36 = 3.67 for 1L year. If this student then had two more years of grades, you'd repeat the same calculation for each year individually, and then average the three years. So if 2L year gave 3.33 and 3L year gave 3.6, this student would have an overall GPA of 3.53. This is true despite the fact that the years have wildly different numbers of credits; each year is of equal weight regardless.
LATIN HONORS CUTOFFS
Historically, the magna cutoff has been approximately 3.96; the cum laude cutoff has been around 3.60. viewtopic.php?t=203988&start=25