Immigration and the struggles at the US-Mexico border were the focus this past week. The head of Trump's Department of Homeland Security, Kirstjen Nielsen, handed in her resignation after apparently facing pressure to comply with Trump's requests despite her concerns about their efficacy and legality. Stephen Miller has replaced her. Nielsen joins a long list of employees who have left the Trump administration, which has the highest turnover on record.

Trump also noted via Twitter that he is "giving strong consideration" to adopting a plan for undocumented immigrants that his own administration rejected on liability, logistics, and budgetary grounds - as well as a fear of bad PR. The plan would entail detaining undocumented immigrants at the border, busing them to Democratic "sanctuary cities" that have refused to comply with Trump's directives to have their local police forces actively help ICE, and leaving them there while they await the results of their asylum cases. The plan was previously suggested in November 2018 and February 2019, but shot down each time in review because, as Trump so eloquently put it, it'd be "so illegal." According to reports, this was one of multiple points of contention between Trump and Nielsen.

Meanwhile, the Justice Department has proposed reviving a Bush-era regulation that would let appellate immigration judges issue binding rulings on the entire immigration system with the involvement of only a minority of appeals judges. This would help Trump's immigration policies survive the court system, since they've previously had their policies challenged or blocked by appellate judges. As expected, Barr - a Trump loyalist and fan - is otherwise committing himself to the Republican agenda, forming an investigative team to determine if anti-Trump and anti-conservative bias within the Justice Department and the FBI played a role into the decision to start the Mueller investigation into the Trump campaign's suspected collusion with Russia. Barr also suggested - with no evidence - that the FBI spied on Trump's campaign.

WikiLeaks founder Julian Assange was finally arrested this week after hiding out in the Ecuadorean Embassy in London for almost seven years. The US will seek to extradite Assange for compromising classified information. Although Trump previously praised WikiLeaks - and indeed once said in 2016 that he "loved" it - for leaking damaging information from the rival Democratic party, such as emails from Hillary Clinton and the Democratic National Committee's internal correspondence, Trump now says that he "know[s] nothing about WikiLeaks."

The Trump administration and Democrats are gearing up for a fight about Trump's tax returns. The Treasury Department deliberately missed a deadline set by Congressional Democrats to provide six years of Trump's tax returns. They're using a little-used but unambiguously worded provision of the law that they argue gives the House Ways and Means Committee the authority to request and review the tax returns of any US citizen. Treasury Secretary Mnuchin indicated that he needs more time to review the legality of the request and expressed his concerns about overreach and privacy. Trump has refused to release his tax returns, saying that he will not do so because he is under IRS audit. There is no provision of the law that states tax returns under audit cannot be released. It is customary for presidents assuming public office to submit their tax returns to public scrutiny.