Opinion on Eagle Act, Religious Freedom Restoration Act, and Indians
Here, in pdf. Altho it construes a statute, it applies a number of constitutional standards. When I was at Interior, I worked with some of these issues. The Eagle Protection Act generally outlaws intentionally killing eagles or using their parts. Certain Indian tribes consider them essential to various religious services. To try to deal with that, Interior puts dead eagles (road kill, mostly) into a repository and rations out feathers, etc.
Problem here was that this tribe maintained that the eagle being offered to the Almighty must be pure, i.e., not road kill. In fact, the stricter adherents maintained the eagle must be captured live by a person. Having seen their claws and beaks, I think I'd contract that job out.