The inelastic electron-electron scattering rate in strongly coupled quantum wells is investigated. Both intrasubband and intersubband scattering processes are considered. The theoretical results are compared with experimental data obtained from the analysis of the resistance resonance measured on GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As heterostructures in the presence of an in-plane magnetic field. A good agreement with the theoretical curves is obtained. The range of validity of the picture presented is discussed critically. \textcopyright{} 1996 The American Physical Society.