Phillipa Lawson of the Canadian Internet Policy and Public Interest Clinic has a thing or two to say about the practice of taking thumbprints from LSAT test-takers:
blog*on*nymity - blogging On the Identity Trail: Mandatory thumbprinting for the LSAT: an appropriate use of biometrics?:
...In any case, LSAC must still explain why other, less intrusive identification methods (such as the presentation of photo ID) are inadequate for the purpose of deterring fraud. Perhaps it is necessary to collect and store individual identifiers for some time after the test is administered, in order to be able to authenticate identities after the fact, in response to allegations of fraud. If so, are non-digitized thumbprints the least intrusive method? ...
For some additional background, see: The Canadian Privacy Law Blog: Complaint about LSAT fingerprinting