Why Did Pope Leo Xiii Endorse Worker Collective Bargaining? Sportslaw blogger.com, April 20, 2024. Pope Leo XIII’s Rerum Novarum, issued in 1891, emphasized the rights of workers to form unions and engage in peaceful strikes. He argued that employers should respect their workers’ right to organize and give in to their [just] demands. The first… Read More Socialism No. Labor Unions Definitely Yes.