Conor, who dated the 'We Are Never Ever Getting Back Together' singer last summer, was reportedly hauled away in handcuffs and taken into police custody, along with his father and actress Daryl Hannah for protesting with Sierra Club outside the White House in Washington DC.
They were protesting against the proposed Keystone XL tar sands pipeline and were released after paying a fine reported Huffington Post.
"After being taken away from the White House in handcuffs, both Kennedys were driven to a Park Police station and released after paying a fine," a press release from the Sierra Club, said.
The 18-year-old student, whose mother Mary Richardson Kennedy committed suicide last year, and his father are long time activists.
Swift and Conor were first spotted together in July and the blonde beauty was said to have missed him so much when she left him in Massachusetts to go home to Nashville over the summer that she chartered a private jet so he could visit.
The couple split when Conor returned to school in September but are said to have remained good friends.