  We propose a new scheme of spin filtering employing ballistic nanostructures
in two dimensional electron gases (2DEGs). The proposal is essentially based on
the spin-orbit (SO) interaction arising from the lateral confining electric
field. This sets the basic difference with other works employing ballistic
crosses and T junctions with the conventional SO term arising from 2DEG
confinement. We discuss the consequences of this different approach on
magnetotransport properties of the device, showing that the filter can in
principle be used not only to generate a spin polarized current but also to
perform an electric measurement of the spin polarization of a charge current.
We focus on single-channel transport and investigate numerically the spin
polarization of the current.
