A Native American was stopped by a federal officer just outside a national park. The federal officer could see, in plain view, an eagle feather on the passenger-side seat next to the Native American. The Native American told the officer that the eagle feather would be used in a religious ceremony. The federal officer arrested the Native American for illegal possession of an eagle feather in violation of the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act. Generally, under federal law, the possession, sale, and use of eagle feathers is prohibited, except that a Native American may possess and use eagle feathers if the Native American is an enrolled tribal member and the possession and use is for religious or cultural purposes. What else must the Native American show to avoid a conviction?