  It is by now established that neutrino oscillations occur due to non-zero
masses and parameters in the leptonic mixing matrix. The extraction of
oscillation parameters may be complicated due to subleading effects such as
non-standard neutrino interactions (NSI) and one needs to have a fresh look how
a particular parameter value is inferred from experimental data. In the present
work, we focus on an important parameter entering the oscillation framework -
the leptonic CP violating phase $\delta$, about which we know very little. We
demonstrate that the sensitivity to CP violation gets significantly impacted
due to NSI effects for the upcoming long baseline experiment, Deep Underground
Neutrino Experiment (DUNE). We also draw a comparison with the sensitivities of
other ongoing neutrino beam experiments such as NOvA, and T2K, as well as a
future generation experiment, T2HK.
