WARSAW, Poland—Poland’s government on Monday defied an injunction by the top European Union court that ordered the immediate closure of a major brown coal mine, with officials saying it would shake the nation’s energy system and lead to the layoff of thousands of employees. Development Minister Jaroslaw Gowin said Poland wouldn’t shut the lignite mine in Turow, on the border with Germany and the Czech Republic, but instead was engaged in “very intensive diplomatic and law-related efforts,” to secure undisturbed operation of the mine and connected power plant that generates some 7 percent of Poland’s energy. The EU’s Court of Justice on Friday ordered Poland to immediately stop operation of the mine, heeding Prague’s complaints that it drained groundwater from Czech territory and that Poland recently extended its license without proper prior environmental assessment. It’s a temporary measure, pending the court’s full ruling. Gowin said he considers the court’s decision …