It's estimated that approx 60% of employers use social media to screen potential candidates, according to a survey done by CareerBuilder. But they could be in breach of European law in the future as EU data protection policies are tightening.
Peter Church, a technology specialist at law firm Linklaters, told the BBC that the UK already had guidelines on employers' use of social media. "Demanding passwords or making a friend request is unacceptable, but it is more difficult when it comes to public facing information," he said. "The general rules are that employers should inform applicants if they are going to look at social media profiles and give them the opportunity to comment. The searches should also be proportionate to the job being applied for." He added that social network LinkedIn was "fair game" because it was set up as a way of advertising yourself as a potential employee.