STRASBOURG — The European Parliament is poised on Tuesday to shield a senior German lawmaker from investigation, reigniting allegations that MEPs are abusing parliamentary immunity to protect their own. The full Parliament will vote on whether to back a decision by the Legal Affairs Committee (JURI), which agreed on May 2 not to lift the immunity of Angelika Niebler, the head of the Christian Social Union delegation in the European People’s Party. The European Public Prosecutor’s Office and a