Filmmaker Laura Poitras, who won an Oscar for her film “Citizenfour” about Edward Snowden, is suing the U.S. government to find out why she has been detained, searched and interrogated more than 50 times at airports. The interrogations took place over six years, beginning in 2006 when Poitras finished her documentary “My Country, My Country” about post-invasion Iraq. Poitras said she was suing “in support of the countless other less high-profile people who have also been subjected to years of Kafkaesque harassment at the borders.”