A long day is expected in San Antonio on Monday as U.S. District Judge Orlando Garcia hears a lawsuit over Texas’ controversial new immigration enforcement law. The measure, known as Senate Bill 4 or the “sanctuary cities” ban, has drawn fierce opposition in recent weeks as lawsuits and press conferences have piled up. Expect more fireworks as the day continues, and follow Texas Tribune reporters Julián Aguilar and Alana Rocha for updates.

Here’s what you need to know: 

• A quick refresher. SB 4 was one of the most divisive pieces of legislation during the legislative session that ended in May. The measure, which takes effect Sept. 1, will allow local law enforcement to question legally detained or arrested people about their immigration status and punish officials who don’t cooperate with federal immigration authorities, subjecting sheriffs, constables, police chiefs and other local leaders to Class A misdemeanor charges. SB 4, which also applies to public colleges, mandates civil penalties for groups that violate the provision, beginning at $1,000 for a first offense and rising as high as $25,500 for each infraction that follows.  
• How did we get here? The day after Texas Gov. Greg Abbott signed SB 4 into law, the city of El Cenizo and Maverick County sued Texas kicked off the lawsuit, saying the bill violated the Texas and U.S. constitutions. Others were quick to follow, and the cities of Dallas, Austin and San Antonio, along with other municipalities and local governments, soon joined the lawsuit opposing the law. Houston — the largest city in Texas — signed onto the suit last week. 
• As the fight against SB 4 has grown, support has, too. The Trump administration waded into the legal battle last week, with the Justice Department filing a statement of interest that argued SB 4 was constitutional and not pre-empted by federal immigration law. Abbott made SB 4 one of his emergency items during the regular legislative session, and defended the legality of the measure upon signing it, saying certain provisions of SB 4 have “already been tested at the United States Supreme Court and approved there.” He also said the law was especially needed after Travis County Sheriff Sally Hernandez announced in January her department’s intentions to reduce cooperation with federal immigration enforcement. SB 4 supporters say it will crack down on illegal immigration and make the state safer. 

• Not so fast, opponents say. Some Democrats and immigrants’ rights groups liken SB 4 to “show-me-your-papers”-type legislation, arguing that the law, once in effect, would unfairly target people in the state and open the door for racial profiling. SB 4 also breaches the guarantees of equal protection and freedom of speech in the Constitution, opponents argue. A lawyers’ group announced in June it was relocating its convention set for next year from Texas — an event expected to draw around 3,000 people — because SB 4 was one of the “dangerous, destructive and counterproductive proposals” that went against the group’s mission. 
  
• The scene at the courthouse is a lively one. According to Texas Tribune reporter Alana Rocha, two buses’ worth of people against SB 4 brought signs to protest the law. “No hate in our state,” said one sign. “Texas I.C.E./Police = Gestapo?” said another. State Sens. Sylvia Garcia, D-Houston, and José Rodríguez, D-El Paso, were spotted outside the courthouse before the hearing. Texas Democrats had warned of “an #SB4 court battle,” Rodríguez told the El Paso Times, adding he was “confident” the measure was unconstitutional. 
• This may only be the beginning. Texas Attorney General Ken Paxton filed his own lawsuit the day after Abbott signed SB 4, requesting a federal court declare the new law constitutional — a move taken in hopes of curbing further pushback from those against SB 4. A court in Austin is considering Paxton’s request Thursday. A lot can happen between now and Sept. 1, but for Monday’s hearing, “expect a long day,” per Aguilar. 

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