Amarillo, Texas, is known for its abundance of cattle, a local restaurant’s 72-ounce steak-eating challenge and, along an interstate highway, a vibrant drug trade. It is the narcotics traffickers who fill the town’s federal courthouse. Judge Matthew Kacsmaryk, appointed by Donald Trump, spends most days overseeing trials about fentanyl pills and powdered meth. But his rulings on several spicier cases have made the 47-year-old a conservative darling far beyond the Texas panhandle.