The background to this story lies in Lennon’s left wing activism and the US government’s paranoia.
Lennon supported various left wing causes; He was anti Vietnam War, pro John Sinclair. When asked about the Bloody Sunday massacre he said that given the choice between the British Army and the IRA he would side with the IRA. It should be noted, however, that Ono specifically denied that Lennon gave financial aid to the IRA when a former member of M15 suggested it.
Lennon’s anti war activities were the direct cause of the deportation order being issued against him. Richard Nixon felt that Lennon’s reported intention to appear at an anti war concert that would coincide with the Republican’s national congress would work against him and his re-election. A deportation order was issued shortly after.
Those were strange times, a rock star could threaten US democracy? Given what Nixon went on to do if only Lennon did have that much power.
The original ‘reason’ for the deportation order was Lennon’s conviction on a misdemeanor ‘charge of possessing a small amount of dope in 1968. Eventually, after 3 and a half years of litigation the deportation order was thrown out when the court said ” … the courts will not condone selective deportation based upon secret political grounds.”
The battle continued until after Nixon was forced to resign. He was succeeded by Gerald Ford. Ford could not see the point of the deportation attempts and they were finally dropped in 1975. In 1976 the green card was issued.