Here is the petition in Perkins v. Commissioner of Internal Revenue:

Perkins v. Commissioner Cert Petition

Question presented:

This Court is presented with a question of first impression, as to the taxability of income derived from the sale of sand and gravel, mined from treatyprotected land by an enrolled member of the Seneca Nation of Indians (“Seneca Nation”). Upon the granting of certiorari, the Court will examine the language in two federal treaties, promising not to disturb the “free use and enjoyment” of lands by the Seneca Nation and “their Indian friends residing thereon and united with them,” and protecting these lands “from all taxes” for any purpose. Treaty with the Six Nations (“Canandaigua Treaty”), art. III, Nov. 11, 1794, 7 Stat. 45; Treaty with the Senecas (“1842 Treaty”), art. 9th, May 20, 1842, 7 Stat. 590. Congress has explicitly stated the Internal Revenue Code “shall be applied to any taxpayer with due regard to any treaty obligation of the United States which applies to such taxpayer.” 26 U.S.C.A. § 894 (a)(1)(West).

The question presented is whether the United States Court of Appeals and the United States Tax Court have given “due regards” to the treaty obligations of the United States by finding these treaties had no textual support for an exemption from federal income tax applicable to an enrolled Seneca member whose income is derived from the
lands of the Seneca Nation. Perkins v. Comm’r, 970 F.3d 148, 162-67 (2d. Cir. 2020).

Lower court materials here.

UPDATE (5/1/21):

Starna Amicus Brief