What percent of Native American Indian does someone have to prove they
have in their ancestry before they can legally be called an Native
American Indian by a judge of the court system in the USA? The reason
I want to know is I am trying to start a business on a Indian
Reservation to help them. I know both sides of my family have American
Indian in them. I know I have probably less than 10% in me and I don't
want to hire a geneologist if I have to have more than 10% to make the
requirement.

Hello.

There's not a single, fixed percentage of Native American ancestry
required to be legally called a Native American or American Indian.
The Census Bureau will count anyone as an American Indian or Native
American who self-identifies as such.

However, to be eligible for services of the Bureau of Indian Affairs
on Indian reservations, certain requirements must be met.

According to the U.S. Government's Bureau of Indian Affairs:

"No single Federal or tribal criterion establishes a person's identity
as an Indian. Government agencies use differing criteria to determine
who is an Indian eligible to participate in their programs. Tribes
also have varying eligibility criteria for membership. To determine
what the criteria might be for agencies or Tribes, you must contact
each entity directly.
 
To be eligible for Bureau of Indian Affairs services, an Indian must
(1) be a member of a Tribe recognized by the Federal Government, (2)
one-half or more Indian blood of tribes indigenous to the United
States (25 USC 479) ; or (3) must, for some purposes, be of one-fourth
or more Indian ancestry. By legislative and administrative decision,
the Aleuts, Eskimos and Indians of Alaska are eligible for BIA
services. Most of the BIA's services and programs, however, are
limited to Indians living on or near Indian reservations."
"
Source Bureau of Indian Affairs "Frequently Asked Questions" on the
web site of the U.S. embassy in Germany (PDF format so the Adobe
Acrobat reader is required):
http://www.usembassy.de/usa/etexts/soc/bia.pdf

Similar information is available on the web site of Infoplease.com:
http://www.infoplease.com/ipa/A0192524.html
Since you don't meet either the one-half (50 percent) or one-fourth
(25 percent) requirements mentioned above, your best bet would seem to
be to try to join a tribe for which you are eligible.

From the Bureau of Indian Affairs "Frequently Asked Questions":

"How does an Indian become a member of a Tribe?
A Tribe sets up its own membership criteria, although the U.S.
Congress can also establish tribal membership criteria. Becoming a
member of a particular Tribe requires meeting its membership rules,
including adoption. Except for adoption, the amount of blood quantum
needed varies, with some Tribes requiring only proof of descent from
an Indian ancestor, while others may require as much as one-half."

search strategy: "what is an indian", "blood quantum", "indian
affairs"

I hope this helps.

You don't have it, the standard for tribal enrollment of the tribe you
are seeking to help (on that reservation) will be the standard for
you.  The legal questin for the Circuit court or Supreme Ct. in your
area will be what is the standard or average and if you can't approach
1/4 you cannot go the direction you wish.  Many citizens in the
Western US can claim somewhere in the 1/8 and below as time goes
onward, but the standard is 1/4-1/3.  You don't need a court
reference, the judge will use the standard of the tribe represented.

There is both a federal recognition status and a tribal. Federal
recognition is by a definitive, proven blood quantity, (1/216th or
better) and despite the fact one can bePROVEN to be descended, one
cannot be federally recognized with less than that amount. Federal
recognition is often  in the benefit of the tribe, rather than the
individual, and one must be demonstrated to be a tribal (not federal)
member to gain any issuances as per treaty or supervision and support
money.

Tribal recognition varies from tribe to tribe, and runs from specific
blood quantity to direct descendency (both require documented proof)
Contacting specific tribes can assist you in determining legal
acceptable tribal affiliation. Many tribes are realizing that blood
quantity was intended to eventually ensure the destruction of tribal
affiliation, and many tribes are working on systems of organizing or
restructuring their recognition methodologies. Tribes can create their
own methodology once they hold tribal sovereignty as a recognized
tribe with the US government.

In essence, the term "legal" Indian can be answered either tribally,
or federally,.... and it depends upon what purpose you intend using
that status for.