On Aug. 29, a federal judge in San Antonio issued a preliminary injunction against most of SB4, the anti-Sanctuary Cities law that was set to go into effect two days later. The law would have effectively forced every police agency in Texas to allow its officers to question the immigration status of anyone stopped for any reason. It would have also have forced agencies to send information on undocumented or out-of-status detainees to US Immigration and Customs Enforcement. Those agencies that instructed officers to ignore the law would be subject to large fines, and the heads of those agencies could face firing or even jail. The law would also force police agencies to hold detainees suspected of being undocumented if ICE so requested, even if those people were due to be released or had paid a bond.

A 29-year-old man believed to be the godson of imprisoned Mexican narco lord Joaquin "El Chapo" Guzmán was indicted on drug charges in a San Diego federal court on Aug. 7. Damaso López Serrano AKA "Mini Lic" was charged with smuggling unspecified quantities of methamphetamine, cocaine and heroin. He'd turned himself in to US border agents several days earlier, and is said to be the highest-ranking Mexican kingpin ever to surrender in the territory of the United States.

After President Donald Trump's inauguration, Mexico saw a wave of angry protests against his proposed border wall, with more than 20,000 marching in Mexico City on Feb. 12, chanting "Pay for your own wall!" But now this wave of anger is crystalizing around concrete legal initiatives that could be very problematic for the White House. First, the front-runner for next year's Mexican presidential election, the left-populist Andres Manuel López Obrador, has filed a complaint with the Inter-American Commission on Human Rights against the proposed wall.

US Department of Homeland Security Secretary John Kelly officially issued two memoranda Feb. 20 directing the department's workforce to implement two executive orders on the enforcement of immigration laws. The first memorandum (PDF) implements President Donald Trump's "Border Security and Immigration Enforcement Improvement Policies" executive order. Kelly directed US Customs and Border Protection (CBP) to hire 5,000 additional Border Patrol agents. This memo orders the immediate identification and allocation of sources of available funding for the construction of a wall along the Mexican border. A standardized method will also be developed for public reporting of data regarding aliens apprehended near the border for violations of immigration law.

Amid rapidly deteriorating relations between the US and Mexico, reports are emerging that President Donald Trump openly threatened military intervention in a phone call with his counterpart Enrique Peña Nieto. According to a partial transcript of the conversation obtained by the Associated Press, Trump told Peña Nieto: "You have a bunch of bad hombres down there. You aren't doing enough to stop them. I think your military is scared. Our military isn't, so I just might send them down to take care of it." ("Bad hombres" is a term Trump also used in his final debate during the presidential campaign to refer to Mexican narco-gangs.)

The planned meeting in Washington between President Trump and his Mexican counterpart, Enrique Peña Nieto, was called off after Trump signed his Jan. 25 executive order decreeing construction of a wall on the border—accompanied with more bluster about how Mexico will pay for it. Since the cancelation, Trump and Peña Nieto have engaged in an unseemly Twitter war, each taking responsibility for calling off the meeting. Things got worse when the White House raised the option of making Mexico pay for the wall with a 20% tariff on all goods coming in from our southern neighbor. The threat portends a trade war with the United States' third biggest trading partner.

President Donald Trump on Jan. 25 signed two executive orders on immigration, marking the beginning of Trump's efforts to fulfill his controversial immigration policy. The first order, titled "Enhancing Public Safety in the Interior of the United States," calls for, among other things, withholding federal funding to cities that provide safe haven to immigrants who have illegally entered the US. The second order, titled "Border Security and Immigration Enforcement Improvements," directs the construction of a wall along the Mexican border and an increase in the number of enforcement officials to remove undocumented immigrants. Although the order calls for "immediate construction of a physical wall on the southern border," it does not address construction costs, which Trump has continually said would fall to the Mexican government. Trump intimated that Mexico would be willing to pay for the wall because it would lessen the number of people who travel through Mexico from more southern countries to reach the US.

President-elect Donald Trump is reported to have named the former chief of the Pentagon's Southern Command, Gen. John Kelly, as his choice for secretary of Homeland Security. As SouthCom chief, Kelly oversaw counter-narcotics operations throughout Central and South America and the Caribbean from late 2012 until his retirement in January 2016. He was a notorious hardliner, which resulted in policy clashes with President Obama, the Washington Post tells us. As Homeland Security chief, he will oversee the 20,000-strong Border Patrol, with responsibility for drug interceptions along the 2,000-mile frontier with Mexico.