I heard this term used for the first time today by one of the Cree teachers. Once it was used an an exclusionary term/concept, but it now seems to have become and accepted way, by some, to determining who can be labelled First nation. I
I've listed the wiki page, and it refers to how it was is used in the States, but it seems to be gaining popularity here. pay attention to the section of what determines membership in a tribe.....1/2, 1/4, 1/8, 1/16, 1/32(equivalent to one great-great-great-grandparent) up to membership by lineal descent(no minimum blood quantum requirement, but members must be able to document descent from original enrollees of tribal rolls).
What the hell happens if this ever comes to pass in Canada? Time for us all to get DNA testing. I've had family in North America since the last decade of the 1600s, so maybe I can score some benefits.
As it currently stands, according to a friend who received his status at age 19 (his maternal grandfather was white/mixed, his dad was white) his kids could marry whites and still be eligible for status, but their kids couldn't unless they married someone with status.
http://en.wikipedia.org/wiki/Blood_quantum_laws