So it was not a shock when, in March, Gorsuch hopped on board with the liberal justices to deliver a win to the Yakama Nation in Cougar Den. In that 5–4 decision, the court had to interpret an 1855 treaty in which the Yakamas surrendered 10 million acres of their land—a quarter of present-day Washington state—in return for, among other things, “the right, in common with citizens of the United States, to travel upon all public highways.” Today, Washington imposes a tax on gasoline brought into the state on a highway. The tribe claimed an exemption from that tax, arguing that the treaty envisioned a sweeping right to bring goods freely to the tribal market.

Siding with the Yakamas, Gorsuch explained that when the court is “dealing with a tribal treaty,” it must “give effect to the terms as the Indians themselves would have understood them.” He pointed out that the federal government “drew up this contract” and employed its “power of the pen” to “its advantage.” Citing findings in an earlier case, he wrote:

During the negotiations “English words were translated into Chinook jargon … although that was not the primary language” of the Tribe. After the parties reached agreement, the U. S. negotiators wrote the treaty in English—a language that the Yakamas couldn’t read or write. And like many such treaties, this one was by all accounts more nearly imposed on the Tribe than a product of its free choice.

Gorsuch explained that in the Yakama language, the phrase “in common with” actually meant “[for] general use without restriction.” Thus, they believed the treaty gave them “the right to travel on all public highways” without being taxed “while engaged in the transportation of tribal goods.” As a result, Washington may not tax gas that Yakamas import onto tribal land via highways. Gorsuch concluded:

Really, this case just tells an old and familiar story. The State of Washington includes millions of acres that the Yakamas ceded to the United States under significant pressure. In return, the government supplied a handful of modest promises. The State is now dissatisfied with the consequences of one of those promises. It is a new day, and now it wants more. But today and to its credit, the Court holds the parties to the terms of their deal. It is the least we can do.

https://slate.com/news-and-politics/2019/05/neil-gorsuch-supreme-court-tribal-rights-sonia-sotomayor.html

(http://www.autoadmit.com/thread.php?thread_id=4580136&forum_id=2#40574750)