For months, the Standing Rock Sioux Tribe in North Dakota has been waging a pitched battle against a proposed oil pipeline that would run near their reservation — arguing that it would endanger both their water supplies and sacred sites.

These protests have become a huge, huge story. The fight over the Dakota Access Pipeline encompasses everything from the federal government’s historically appalling treatment of Native Americans to broader debates about fracking and climate change. The cause has attracted an array of tribes, activists, and environmentalists around the country, and authorities have been clashing with protestors all summer.

On Sunday, these clashes turned violent when law-enforcement officials used water cannons on protesters in freezing weather — sending some 26 people to the hospital with bone fractures or hypothermia. This came after an earlier major confrontation on October 27, when activists occupied private land along the pipeline’s proposed route, arguing that it actually belonged to the tribes under an 1851 treaty with the US government that hasn’t been properly honored. In response, police used rubber bullets, pepper spray, and water cannons to disperse the protestors, arresting 141 people in all.

Opponents have also taken the fight to court, hoping to alter or block the pipeline. The DC Circuit Court is currently hearing a major legal challenge to the project, with the Standing Rock Sioux arguing that the Army Corps of Engineers did not properly consult them before green-lighting the section near their reservation.

The pipeline is now 75 percent complete, but it’s hit some serious roadblocks. On September 9, the Obama administration ordered the Army Corps of Engineers to pause further permitting and revisit the controversial section nearest the reservation. Then, on November 2, President Obama said that officials are looking into possible ways to reroute the project, though a decision could take weeks. The pipeline company, for its part, is hoping Donald Trump will approve the project when he comes to office.

All the while, protests continue to grow. So here’s a guide to how we got this point.

What is the Dakota Access Pipeline?

The pipeline in question was first proposed in 2014 by Dakota Access, a subsidiary of Texas-based Energy Transfer Partners. If built, it would carry some 450,000 barrels of crude per day from the Bakken oil fields in North Dakota down to a terminal in Illinois, where it could be shipped to refineries and turned into usable fuel.

The whole thing would stretch 1,134 miles underground and cost some $3.8 billion:

The rationale behind this project is straightforward. Since the late 2000s, drillers have been using fracking techniques to exploit vast new deposits of oil in the shale formations of North Dakota. Crude oil output has surged, and the state has become one of the epicenters of the recent US oil boom.

But because this all happened so quickly, there weren’t sufficient pipelines to carry all that new oil to market. Instead, North Dakota’s drillers have been shipping thousands of barrels of crude each day by trains, which are costlier and also sometimes get derailed and explode. Oil companies would prefer a cheaper, quieter pipeline, especially now that crude prices have dropped and profits are thinner. Hence the proposal.

Why is the Dakota Access pipeline so controversial?

Although oil pipelines are less accident-prone than trains, they’ve certainly been known to leak, with destructive results. So there’s been scattered complaints about the proposed route ever since late 2014, starting with farmers in Iowa.

But by far the biggest source of opposition has been in North Dakota, around the portion of pipeline that would run just north of Sioux County and the Standing Rock Indian Reservation, home to 8,250 people. See the map below (which is based on Carl Sack’s great map at the Huffington Post):

For months, members of the Standing Rock Sioux have raised two major concerns about the project:

First, the pipeline would cross right under the Missouri River at Lake Oahe, half a mile north of the reservation. A leak or spill could send oil directly into the tribe’s main source of drinking water. The tribe points out that Dakota Access originally considered a route farther north, upstream of Bismarck, but the company rejected that route, in part, because of the close proximity to the state capital’s drinking-water wells.

Second, the tribe argues that the pipeline would run through a stretch of land north of the reservation that contains recently discovered sacred sites and burial places. True, this land isn’t part of the current reservation. But the Standing Rock Sioux argue that the land had been taken away from them unjustly over the past 150 years. And any bulldozing and construction work could damage these sites.

As such, the tribe has called on the pipeline to be rerouted or reconsidered altogether. (In response, Dakota Access has argued that it will employ “new advanced pipeline technology” to limit leaks — and that it will take care to protect any cultural sites.)

More to the point, the Standing Rock Sioux argue that under federal law, the US government should have consulted extensively with the tribe about these issues — and didn’t. On July 27, the Standing Rock Sioux and the nonprofit Earthjustice sued the Army Corps of Engineers in federal court, arguing that the agency had wrongly approved the pipeline without adequate consultation.

As journalist Aura Bogado explains, at the core of this dispute is the concept of “tribal sovereignty.” The US government is supposed to have a “government-to-government” relationship with native tribes — not run roughshod over them.

What are the Dakota Access pipeline protests?

Since March, thousands of Native Americans from across the country have come to Cannon Ball to camp out and protest the pipeline in solidarity with the Standing Rock Sioux.

The fight has attracted the interest of climate activists and environmentalists, who have been focused on blocking new fossil fuel infrastructure, particularly after their victory in stopping the Keystone XL pipeline last year. It’s also pulled in politicians like Bernie Sanders and Jill Stein. (Hillary Clinton, by contrast, has avoided taking a stand.)

The last few months in particular have seen the battle intensify. This new phase began around August 24, after the Standing Rock Sioux asked the DC Circuit Court for an injunction to halt activity on the pipeline while their broader lawsuit against the project was resolved (a lawsuit that could take a year or more).

Then, on September 3, shortly after the injunction was requested, Dakota Access deployed bulldozers and began digging up the section of the pipeline route that contained possible native burial artifacts — widely viewed as an attempt to circumvent the lawsuit and make the pipeline inevitable. Protesters tried to stop the bulldozers, and there’s video of private security responding with dogs and pepper spray.

Five days later, North Dakota Gov. Jack Dalrymple activated the state National Guard "in the event they are needed to support law enforcement response efforts."

In October, protestors began occupying a portion of privately owned land just north of the reservation that lay directly in the pipeline’s path. They’ve argued that this slice of land actually belongs to Native Americans under the Fort Laramie Treaty of 1851, signed between eight tribes and the US government — a treaty that was subsequently violated after Congress unilaterally took back territory over the years. “We have never ceded this land,” said Joye Braun of the Indigenous Environmental Network in a statement.

The protestors on the private land say their demonstrations have been peaceful, featuring prayers and chants and drum circles. But local authorities have cracked down hard on these intrusions: On October 27, police used pepper spray, water cannons, and bean bags to push back the activists, arresting more than 141 people in all.

On November 21, the clashes took another violent turn as law enforcement officials used water cannons in subzero temperatures to beat back a crowd of 400 people. (The Morton County sheriff’s office claimed that protestors had been setting fires.) According to the Guardian, at least 26 people were hospitalized — some with bone fractures, most with hypothermia.

What’s the lawsuit over the pipeline all about?

While the protests rage on, there’s also a court case winding through federal courts that could decide the ultimate fate of the pipeline. The case centers around the Army Corps of Engineers, the federal agency that typically approves interstate pipelines and provides permit for water crossings.

By law, any federal agency overseeing a construction project has to consult with native nations or tribes if there are places with “religious and cultural significance” nearby. (This is true even if those places are not explicitly part of a reservation — a recognition that many tribes have been forcibly relocated by the federal government and have had their lands taken over the years.)

In their complaint, filed on July 27, the Standing Rock Sioux argued that the Army Corps of Engineers handed out water permits too hastily and only consulted with the tribe on a narrow set of potential impacts. (The tribe ended up sitting out much of the consultation process in protest.) The tribe also argued that Dakota Access used out-of-state experts to survey the lands beforehand, and so missed a whole bunch of culturally significant archaeological discoveries along the pipeline’s path.

You should read Robinson Meyer in the Atlantic for much more on the legal merits of the case. He argues that the Standing Rock Sioux have a reasonable case — the law is pretty clear that native nations or tribes need to be consulted extensively, in a “government-to-government” fashion. But it’s far from clear they’ll actually win.

This case is currently being heard by US District Judge James E. Boasberg, who was appointed to the federal bench by President Obama in 2011. It could take months to reach a resolution. So, in the meantime, the Standing Rock Sioux and the nonprofit Earthjustice had asked for an injunction to halt construction until a final decision.

On September 9, Boasberg denied that request for an injunction. You can read his reasoning here. He starts by setting the scene: “Since the founding of this nation, the United States’ relationship with the Indian tribes has been contentious and tragic.” But he then goes on to argue that the tribe “has not shown it will suffer injury that would be prevented by any injunction the Court could issue” and that the Army Corps "gave the Tribe a reasonable and good-faith opportunity to identify sites of importance to it."

Immediately after the injunction was denied, however, the Obama administration stepped in and ordered a stop to construction around Lake Oahe until the Army Corps of Engineers could revisit the disputes over this portion of the pipeline. “Furthermore,” the Department of Justice, Department of Interior, and Department of the Army said in a letter, “this case has highlighted the need for a serious discussion on whether there should be nationwide reform with respect to considering tribes’ views on these types of infrastructure projects.”

What happens next for the pipeline?

On November 2, as protests continued, Obama issued another statement saying that the Army Corps “is examining whether there are ways to reroute this pipeline.” He added: “[W]e’re going to let it play out for several more weeks and determine whether or not this can be resolved in a way that I think is properly attentive to the traditions of the first Americans.” (Here’s a piece from E&E on whether rerouting the project is even possible — certainly it would cost developers millions of dollars.)

For now, the portion of the pipeline nearest the reservation remains in limbo and the legal battles will continue. As Earthjustice explains, the broader lawsuit against the pipeline is still moving forward — and may not get resolved before the end of 2016, at least. What’s more, Dakota Access still must get one last bit of approval from the Army Corps of Engineers before digging on either side of Lake Oahe. On November 14, the Army Corps called for “additional discussion” with the Sioux before deciding to grant that final permit.

Looming over all of this, of course, is the specter of Donald Trump. The company behind the project, Energy Transfer Partners, has said that it fully expects Trump’s administration to approve the pipeline come January. The company’s CEO, Kelcy Warren, donated $100,000 to a Trump Victory Fund before the election. (Trump himself reportedly once held stock in Energy Transfer Partners worth over $500,000, though a spokesperson told the Washington Post he sold it off earlier this summer.)

Still, nothing’s settled yet. And, in the meantime, protestors aren’t backing down. Here’s Dave Archambault II, chairman of the Standing Rock Sioux, in September: "We're going to continue to [fight this battle] as long as it takes to try and have this nation recognize the injustices that are being implemented on our nation."

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