  The response to longitudinally polarized electrons in coincident out-of-plane
($\vec{\mathrm e},{\mathrm e}'{\mathrm p}$) reaction is discussed to study the
role of final state interactions and quantum interference between different
reaction channels, i.e. between direct (quasi) elastic proton emission and
baryon resonance production. The high-energy suppression of this effect due to
colour transparency is also discussed. Results are given for the
$^{12}$C($\vec{\mathrm e},{\mathrm e}'{\mathrm p}$)$^{11}$B$_{\mathrm {g.s.}}$
