#askU2 -Did you realize DAPL's installation is probably illegal? -this funds 

There are prominent legal issues on not one, but (at least) two counts, the foremost being the question of whether it's a Treaty violation. It is also illegal to revoke an EIS (Environmental Impact Statement) based on a Presidential Memorandum, especially when you deep six the report that says you had a legal basis for launching the EIS in doing so. There are new, more substantive articles on this, as well as a new report by the UN on the matter.

Violating a Treaty isn't just violating the law, it's a violation of Article VI of the U.S. Constitution.

US Federal Court has now ruled on this, by the way. They've just allowed oil to continue to flow despite finding the pipeline's implementation illegal on several counts.

"The Standing Rock Sioux Claim ‘Victory and Vindication’ in Court

A federal judge rules that the Dakota Access pipeline did not receive an adequate environmental vetting." - The Atlantic

Feds Urge Judge to Keep Oil Flowing in Dakota Access Pipeline During Environmental Review - Ecowatch

To help you identify the bounty of the information trove you've just landed on, the issues that this judge deemed illegal were brought up to substantiate Question #6 (namely the points numbered 6 and 7). Not only were they specifically addressed in the ruling (though the Judge has deemed the USACE's reversal on the EIS to have not been illegal, which would take it right up to the president) - it seems clear that the identified issue of specifically withholding spill modelling and other assessments from the tribe, and how this violated their Treaty rights, was indeed at issue. 

What you have in these hyperlinks (specifically under "a reroute option") is the engineering report authored by tribal engineer Steve Martin that was used by the tribes in their court case. It's a safe inference the court case was won on that basis. The engineering points at issue listed were all obtained from Steve's communications on Facebook, and he vetted my referencing him in my first publication. He has since terminated his account. He considered the HDD pipeline installed under Lake Sacagawea to be just as disturbing if not worse in implementation than the Dakota Access Pipeline. I lost referencing to his full write-ups on both pipelines when he terminated his FB account, but had directed his attention to it in the beginning and offered this summary when published: 

"Steve Martin has more to say about what’s wrong with the DAPL, in the main pointing out how much more the installation of an underground pipeline is compounded by the length under a water body, and safer relative to the distance being shorter, and how this hampers detection systems for leaks. When they’re allowing much worse projects by Phillips 66 to fly (the pipeline under Lake Sakakawea that endangers the drinking water of several North Dakota cities; Steve Martin has plenty more to say about the design flaws and danger on this -namely when longer HDD tunnels are done, there is no protection of the pipe possible in construction (i.e., casing), plus the danger of hydrofracture increases during installation relative to length) -if North Dakota State is granting permission on pipelines like these, it’s not like they care. No one cared about the Phillips 66 pipeline under Lake Sacagawea (Native spelling) in North Dakota, which has already been whistle blown for shoddy construction. Once it’s under, it’s done. There’s no going back. This pipeline is set to service a rail terminal for BNSF trains, so you never heard of it. The Natives didn’t protest that one. They bought in."

-taken from "How Bono's RED Became the Color of Philanthrowashing Done Right for the Dakota Access Pipeline - Part III" - wrongkindofgreen