Decentralized detection problems are studied where the sensor distribu
tions are not specified completely. The sensor distributions are assum
ed to belong to known uncertainty classes. It is shown for a broad cla
ss of such problems that a set of least favorable distributions exists
for minimax robust testing between the hypotheses. It is hence establ
ished that the corresponding minimax robust tests are solutions to sim
ple decentralized detection problems for which the sensor distribution
s are specified to be the least favorable distributions.