A police officer was assaulted in the town centre after attempting to stop a brawl.
Paul Hearn of Westgate in Grantham was seen fighting another man in Butchers Row, Grantham, at around 3am on April 1.
A police officer stepped in but Hearn refused to co-operate and kept walking away from the officer.
The officer took hold of Hearn’s arm but Hearn kept struggling, trying to break the grip.
Daniel Pietryka, prosecuting, described how the police officer refused to let go so Hearn “punched him with his left hand with a closed fist to the right upper arm area”.
Mr Pietryka said Hearn apologised in his police interview and said he “did not mean to do it”.
The court heard Hearn had drunk two pints of lager, Jack Daniels and other spirits prior to the assault.
Hearn, 22, was fined £75 and ordered to pay £85 in costs. He must also pay a surcharge of £20.