Legal rules severely restrict payments to fact witnesses, though the government can often offer plea bargains or other nonmonetary inducements to encourage testimony. This asymmetry is something of a puzzle, for most asymmetries in criminal law favor the defendant. The asymmetry seems to disappear where physical evidence is at issue. One goal of this Essay is to understand the distinctions, or asymmetries, between monetary and nonmonetary payments, testimonial and physical evidence, and payments by the prosecution as opposed to the defense. Another is to suggest ways in which law could better encourage the production of evidence, and thus the efficient reduction of crime, with a relaxation of the rule barring payment.
Available at: http://works.bepress.com/ariel_porat/2/