  The extraction of neutrino oscillation parameters requires the determination
of the neutrino energy from observations of the hadronic final state. Here we
discuss the difficulties connected with this energy reconstruction for the
ongoing experiments MiniBooNE and T2K. We point out that a lower limit to the
uncertainty in the reconstructed energy from Fermi motion alone amounts to
about 15%. The entanglement of very different elementary processes, in this
case quasielastic scattering and pion production, in the actual observables
leads to considerably larger errors. We discuss the sensitivity of the energy
reconstruction to detection techniques and experimental acceptances. We also
calculate the misidentification cross section for electron appearance in the
T2K experiment due to neutral pion production.
