After the scandal of Facebook data-sharing in which it was cite of improperly obtaining information on users. According to Facebook, data about up to 87 million of its members was harvested by a quiz app and then passed on to the political consultancy. This information was then passed on to Cambridge Analytica which has been accused of using it for political campaigning.
Political consultancy maintained that it did nothing wrong in the way it obtained and used the data.
News Sources : BBC News