As applied by courts, the Hand Rule balances the injurer's burden of precau
tion and the victims' reduction in risk. In this application, risk to onese
lf does not increase the duty owed to others. Economists, however, use the
Hand Rule to minimize social costs, which requires balancing the burden of
precaution against the reduction in risk to everyone. For economists, risk
to oneself counts in determining the duty owed to others. In cases where pr
ecaution reduces joint risk (risk to oneself and others), the usual legal i
nterpretation underestimates the reduction in risk relative to the economic
interpretation, often by 50 percent. The consequence is a lower standard o
f legal care than required to minimize social costs. Judges should reconcep
tualize the Hand Rule so that risk to oneself increases the care owed to ot
hers.