Here at IUP (Indiana Univ. of PA) we do circulate journals to faculty,
but only for a 24 hour loan period.  Teaching Assistants are considered
faculty and are given the same priviledges.  Occassionally, a faculty or
TA will need additional circulation time.  Extentions are granted, on a
case-by-case basis, at the discretion of the Serials Librarian.

This system has worked fairly well.  We occasionally have a recalcitrant
faculty who thinks a 24 hour loan period lasts for an entire semester.
We usually can get the material back with some gentle persuasion.  We have
not had to resort to extreme measures, but we would be willing to block such
services as regular book checkout, interlibrary loans, etc. for flagrant
offenders.   If you still can't get the material back, try sending your
institution's form of internal invoice to the offender's department, billing
for replacement costs.  Exchange of "real" money usually makes someone sit
up and take notice.