  We investigate the consequences of the ambiguity of minimal coupling
procedure for Einstein-Cartan gravity with Holst term and fermions. A new
insight is provided into the nature and physical relevance of coupling
procedures considered hitherto in the context of Ashtekar-Barbero-Immirzi
formalism with fermions. The issue of physical effects of the Immirzi parameter
in semi--classical theory is reinvestigated. We argue that the conclusive
answer to the question of its measurability will not be possible until the more
fundamental problem of nonuniqueness of gravity--induced fermion interaction in
Einstein-Cartan theory is solved.
