The Oscar-winning documentary film-maker Laura Poitras is suing the US government. Poitras, 51, said she had been held at borders more than 50 times between 2006 and 2012, often for hours at a time. At various times she alleges being told by officials that she was on a no fly" list, having her electronic equipment confiscated ... and being threatened with handcuffs for taking notes. The latter incident took place when she was working on a film about the WikiLeaks founder Julian Assange. Poitras [is] launching the legal action "because the government uses the US border to bypass the rule of law," said the film-maker. She was repeatedly stopped until 2012, when the journalist Glenn Greenwald wrote an article about her experiences. Poitras's reporting on the NSA whistleblower Edward Snowden, along with work by Greenwald, Ewen MacAskill and Barton Gellman contributed to the Pulitzer prize for public service won jointly by the Washington Post and the Guardian in 2014. Her film on Snowden, Citizenfour, won the 2015 Oscar for best documentary. The director is being represented by lawyers from digital-rights advocacy group the Electronic Frontier Foundation. "The well-documented difficulties Ms Poitras experienced while traveling strongly suggest that she was improperly targeted by federal agencies as a result of her journalistic activities," senior counsel David Sobel told the Intercept. "Those agencies are now attempting to conceal information that would shed light on tactics that appear to have been illegal."