One of the most persistent sources of confusion about capitalization is the issue of capitalizing someone’s title. These days, most style books have taken the journalistic approach to capitalizing titles. When the title comes before the name and is used as part of the name, it is capitalized. U.S. Secretary of State Hillary Clinton. Navajo Tribal Chairman Joe Shirley. Law Professor James Jones.
When the title comes after the name, it is not capitalized. Hillary Clinton, secretary of state. Joe Shirley, tribal chairman of the Navajo Nation.
Note that the organization should be capitalized if the name is used in full as in Navajo Nation. However, if you wrote, Joe Shirley, chairman of the tribe, you would not capitalize tribe.