An important responsibility of emergency departments is the management of i
njuries sustained in assaults. Most assaults, including many causing seriou
s injury, are not reported and: not recorded by the police. This is importa
nt because police investigation and the conviction of offenders has a subst
antial deterrent effect and because information about the circumstances, of
intentional injury is key to prevention. Recent investigation of ED-police
collaboration has shown that many of the injured, and ED staff want offens
es to be reported but that there are attitudinal, logistic, and ethical-leg
al obstacles to achieving this. Organized joint efforts by emergency medici
ne personnel and police departments, on the basis of a sound, legal and eth
ical framework to protect the rights of both victims and offenders, should
deter more violent offenders and would-be violent offenders. They also prov
ide the police with unique aggregate, nonconfidential information that is o
f substantial, help in tackling violence. ED data can be used to measure an
d, refine violence prevention initiatives and are being developed as the ba
sis of a new, independent measure of pol:ice performance. Strategies, pract
ical ideas to overcome obstacles, and directions for future research are su
ggested.