DUBLIN — TikTok on Tuesday began a defense of how it handles Europeans' privacy and data in a court case that will define how Chinese-owned companies in Europe deal with Beijing's spying laws. The popular social media app is going head to head with the Irish Data Protection Commission — Europe's most powerful privacy regulator, which oversees tech giants including Meta, X and Google. At stake in the Irish court battle is whether TikTok is allowed to transfer personal data of Europeans to China.