The European Union’s highest court on Tuesday is to rule in two multibillion-euro legal battles, involving Google and Apple, which are part of Brussels’ fight to stop tax loopholes and rein in US tech giants. In 2016, the European Commission ordered Apple to pay €13 billion ($14.4 billion) in back taxes, arguing that the US company had underpaid taxes due in the bloc following a suspected sweetheart deal with EU member Ireland. Apple filed a successful complaint with the EU’s general court, arguing that the commission had failed to prove that the contested tax deal constituted prohibited state…