entanglement in a solid state environment resides in the fact that electrons in a conductor are not necessarily sufficiently separated from one another for coincidence counting to make sense, like in optical systems. Furthermore, the measurement of single coincidence events in electronic solid state systems does not seem realizable at present. Zero-frequency noise accounts for long time correlations and we do not expect it to be in general sensitive to coincidence measurements (see however the discussion in Ref. [@samuelsson03] for the limit of small transmission rates). From these premises we suggest that FCS is a natural candidate to formulate a Bell-type inequality for electrons in mesoscopic conductors. In the case where only two entangled electrons are injected, we find a situation similar to that with photons. More generally we discuss the case where a large number of electrons have been injected.

In its original version [@bell64], the Bell inequality was derived for dicotomic variables. Here we consider the more general formulation due to Clauser and Horne [@clauser74]. We consider the idealized setup, illustrated in Fig.\[Ent\], which consists of the following parts. On the left we place an entangler that produces $2M$ electrons in a spin entangled state (in Section \[results\] 