Churchill 's subjects are often American Indian figures and other themes associated with Native American Culture . He uses historical photographs as source material for works . In the early 1990s at Santa Fe Indian Market , Churchill protested the passage of the 1990 Indian Arts and Crafts Act . It requires that , to identify and exhibit works as being by a Native American , artists and craftsmen must be enrolled in a Native American tribe or designated by a tribe as an artisan . Under federal law , Churchill cannot identify his art as by a Native American .