Taiwan’s parliament, dominated by the China-friendly opposition, on Tuesday amended a controversial law to expand the lawmakers’ investigative powers, which opponents have slammed as an erosion of democracy. Outside the parliament building, more than 30,000 protesters showed their outrage by giving the move the thumbs-down. “This is a law that is most difficult to operate and enforce because it had never been fully discussed,” Puma Shen, a lawmaker from the ruling Democratic Progressive Party (DPP), said at the legislative session after the passage of the amendment, adding that the legislative…