We calculate, within the pQCD parton model at leading orders, the expressio
n of the polarization P of spin 1/2 hadrons (typically Lambda baryons), pro
duced in polarized semi-inclusive DIS in all possible cases in which weak i
nteractions are involved. We discuss how to gather new information on fragm
entation and distribution functions and give numerical estimates in the cas
es for which data are or will soon be available.