Many questions of legal interpretation hinge on whether two groups of people assign different meanings to the same word. For example: Do 18th- and 21st-century English speakers assign the same meaning to commerce? Do judges and laypersons agree on what makes conduct reasonable? We propose a new statistical test to answer such questions. In three applications, we use our test to (1) quantify differences in the meanings of specialized words from civil procedure, (2) identify statistically significant differences between judges and laypersons’ understandings of reasonable and consent, and (3) assess differences across various effort standards in commercial contracts (phrases like best effort and good faith effort). Our approach may be readily applied outside the law to quantify semantic disagreements between or within groups. (JEL C10, C12, C55, K12, K41).