In thi s paper,Ihave revi ewed di erent strategi es for detecti ng b pol ari zati on e ects through l epton energy spectra i n the i ncl usi ve sem i l eptoni c decays ofb hadrons. I have show n that,i fone concentrate on el ectron and m uon spectra i n the i ncl usi ve b hadrons decay, one has to deal w i th l arge theoreti cal uncertai nti es com i ng from the onl y-parti alknow l edge of the b fragm entati on functi on. A strategy to control these am bi gui ti es that m akes use ofboth LEP and l ower-energy PET R A **data** has been outl i ned. By com pari ng theoreti cal predi cti ons w i th experi m ental data, one can al ready excl ude l arge pol ari zati on e ectsi n the LEP i ncl usi ve l eptoni c spectrum . M uch m ore can be done w i th l arge stati sti cs on the b baryon sam pl e,by restri cti ng the pol ari zati on study to b baryons. In fact,the correspondi ng P e ect shoul d be about an order ofm agni tude l arger than i n the i ncl usi ve hadroni c spectrum ,si nce (contrary to b baryons) b m eson,w hi ch m ake up m ost ofthe hadroni c sam pl e,are expected notto retai n any ori gi nalspi n i nform ati on.In pri nci pl e,w hen restri cti ng to b sam pl es,a real i sti c m odel l i ng ofexcl usi ve decays i s requi red. It has been show n that, i f one can study al so neutri no spectra w i th good accuracy, the new vari abl e y = hE ' i=hE ii sal m ostfree oftheoreti caluncertai nti esand opti m i zesthe sensi ti vi ty to P ,due al so to the very good sensi ti vi ty ofneutri no spectra.