Mods - sorry for editorialising the title, I know it’s against HN rules, but the full ruling title is too long to fit into the heading field. “The operator of a website that features a Facebook ‘Like’ button can be a controller jointly with Facebook in respect of the collection and transmission to Facebook of the personal data of visitors to its website“
Related analysis: https://www.theregister.co.uk/2019/07/29/eu_gdpr_facebook_li...