Prince Harry’s memoir Spare is not “proof” that he took drugs and could have been embellished to “sell books”, a lawyer for the Biden administration has told a US court. The Duke of Sussex’s visa was at the centre of a court case today, as a conservative think tank wants Harry’s US immigration files to be made public. In his memoir Spare, the prince, 39, admitted to formerly taking marijuana, cocaine and psychedelic mushrooms. Drug use can be used as grounds to deny a US visa application, which could threaten Harry’s US immigration status. The Heritage Foundation sued the Department of Homelan…