Question: Because these areas have tribal sovereignty what proposal was approved by 51.51% of the voters on November 5, 1996 by the state of Michigan?

Context paragraphs:
Tatarstani sovereignty referendum, 1992: A sovereignty referendum was held in Tatarstan on 21 March 1992.  Voters were asked whether they approved of Tatarstan being a sovereign state.  The proposal was approved by 62% of voters.

Impact of Native American gaming: Impacts of Native American gaming can be positive or negative, depending on the tribe and its location.  In the 1970s, various Native American tribes took unprecedented action to initiate Native gaming enterprises.  In doing so, they created not only a series of legal struggles between the federal, state, and tribal governments but also a groundbreaking way to revitalize the Native American economy.  Native American gaming has grown from bingo parlors to high-stakes gaming and is surrounded by controversy on many different levels.  There are disputes concerning tribal sovereignty, negative effects of gaming, and a loss of Native American culture.  In the United States the Indian Gaming Regulatory Act was passed in 1988 in order to secure collaboration between the states and tribes and also in order for the federal government to oversee gaming operations.  Native American gaming has proven to be extremely lucrative for several tribes, but it has also been unsuccessful in some instances.  Native American gaming is contingent upon and only beneficial to its respective reservation.

Native American civil rights: Native American civil rights are the civil rights of Native Americans in the United States.  Because Native Americans are citizens of their tribal nations as well as the United States, and those tribal nations are characterized under U.S. law as "domestic dependent nations", a special relationship that creates a particular tension between rights retained via tribal sovereignty and rights that individual Natives obtained as U.S. citizens.  This status creates tension today, but was far more extreme before Native people were uniformly granted U.S. citizenship in 1924.  Assorted laws and policies of the United States government, some tracing to the pre-Revolutionary colonial period, denied basic human rights—particularly in the areas of cultural expression and travel—to indigenous people.

Native American Venture Fund: The Native American Venture Fund (NAVF) is a for-profit, Impact Investment Fund that partners with Native American Tribal Corporations to leverage the tribe’s economic and legal advantages in order to develop successful tribal business enterprises.  These legal advantages are defined as Tribal Sovereignty which are based upon existing laws and treaties to ensure that U.S. state governments and the U.S. federal government live up to their legal obligations to the Native American Tribal Nations.  NAVF's vision is to help all tribal nations become economically self-sufficient by providing access to business opportunities, capital, training and mentor-ship.

Tribal sovereignty in the United States: Tribal sovereignty in the United States is the inherent authority of indigenous tribes to govern themselves within the borders of the United States.  The U.S. federal government recognizes tribal nations as "domestic dependent nations" and has established a number of laws attempting to clarify the relationship between the federal, state, and tribal governments.

Native American gaming: Native American gaming comprises casinos, bingo halls, and other gambling operations on Indian reservations or other tribal land in the United States.  Because these areas have tribal sovereignty, states have limited ability to forbid gambling there, as codified by the Indian Gaming Regulatory Act of 1988.  As of 2011, there were 460 gambling operations run by 240 tribes, with a total annual revenue of $27 billion.

State recognized tribes in the United States: State recognized tribes are Native American Indian Tribes, Nations, and Heritage Groups that have been recognized by a process established under assorted state laws for varying purposes.  With increasing activism by tribal nations since the mid-20th century to obtain federal recognition of their tribal sovereignty, many states have passed legislation to recognize some tribes and acknowledge the self-determination and continuity of historic ethnic groups.  The majority of these groups are located in the Eastern US, as is the case with the three largest state-recognized tribes: viz.  the Lumbee Tribe of North Carolina and the United Houma Nation of Louisiana.

Michigan Gaming Control and Revenue Act: The Michigan Gaming Control and Revenue Act, passed by Michigan voters in 1996 as Proposal E and then expanded and signed into law as the Public Act 69 of 1997, allows non-Native American casino gaming in Michigan.  The proposal was approved by 51.51% of the voters on November 5, 1996.

Ex parte Crow Dog: Ex parte Crow Dog, 109 U.S. 556 (1883) , is a decision of the Supreme Court of the United States that followed the death of one member of a Native American tribe at the hands of another on reservation land.  Crow Dog was a member of the Brulé band of the Lakota Sioux.  On August 5, 1881 he shot and killed Spotted Tail, a Lakota chief; there are different accounts of the background to the killing.  The tribal council dealt with the incident according to Sioux tradition, and Crow Dog paid restitution to the dead man's family.  However, the U.S. authorities then prosecuted Crow Dog for murder in a federal court.  He was found guilty and sentenced to hang.  The Supreme Court held that unless authorized by Congress, federal courts had no jurisdiction to try cases where the offense had already been tried by the tribal council.  Crow Dog was therefore released.  This case was the first time in history that an Indian was held on trial for the murder of another Indian.  The case led to the Major Crimes Act in 1885, which placed some major crimes (initially seven, now 15) under federal jurisdiction if committed by an Indian against another Indian on a reservation or tribal land.  This case was the beginning of the plenary power legal doctrine that has been used in Indian case law to limit tribal sovereignty.

Swiss referendums, 1952: Nine referendums were held in Switzerland during 1952.  The first was held on 2 March on a federal resolution on changing the licensing requirements for new pubs, and was rejected by 54% of voters.  The second was held on 30 March on a federal law on promoting agriculture and the farming community, and was approved by 54% of voters.  The third was held on 20 April on a popular initiative on a "commodity sales tax", and was rejected by 81% of voters.  The fourth was held on 18 May on a popular initiative "for the finance of armaments and the protection of social achievements", and was rejected by 56% of voters.  The fifth was held on 6 July on a federal resolution on the coverage of expenditure on weapons, and was rejected by 58% of voters.  The sixth and seventh were both held on 5 October on making an amendment to the federal law on Aged and Bereavement insurance regarding tobacco tax, and on establishing air raid shelters in buildings.  The first was approved by 68% of voters, whilst the second was rejected by 85%.  The eighth and ninth were both held on 23 November on a limited prolongation of some price controls and a federal resolution on bread supply.  Both were approved by voters.

Supporting paragraphs: Michigan Gaming Control and Revenue Act Native American gaming
Answer: Michigan Gaming Control and Revenue Act