““As a federal district court in Texas recently ruled, federal law “mandates the initiation of immigration removal proceedings whenever an immigration officer encounters an illegal alien who is not ‘clearly and beyond a doubt entitled to be admitted.’” Moreover, the court explained, the Department of Homeland Security does not have “prosecutorial discretion” to ignore this requirement; Congress, not the president, has the plenary power to make immigration law; and the executive branch may not “implement measures that are incompatible with Congressional intent.””