  We consider Non-Standard neutrino Interactions (NSI), described by
four-fermion operators of the form $(\bar{\nu}_{\alpha} \gamma {\nu}_{\beta})
(\bar{f} \gamma f)$, where $f$ is an electron or first generation quark. We
assume these operators are generated at dimension $\geq 8$, so the related
vertices involving charged leptons, obtained by an SU(2) transformation
$\nu_{\delta} \to e_{\delta}$, do not appear at tree level. These related
vertices necessarily arise at one loop, via $W$ exchange. We catalogue current
constraints from $\sin^2 \theta_W$ measurements in neutrino scattering, from
atmospheric neutrino observations, from LEP, and from bounds on the related
charged lepton operators. We estimate future bounds from comparing KamLAND and
solar neutrino data, and from measuring $\sin^2 \theta_W$ at the near detector
of a neutrino factory. Operators constructed with $\nu_\mu$ and $\nu_e$ should
not confuse the determination of oscillation parameters at a $\nu$factory,
because the processes we consider are more sensitive than oscillations at the
far detector. For operators involving $\nu_\tau$, we estimate similar
sensitivities at the near and far detector.
