Dominic Duris, of Blackrock Park, Commons, Belleek, admitted assaulting the officer and spitting on his uniform.
He was released on £500 bail pending the outcome of an appeal against the prison sentence.
Charges that he was in possession of a kitchen knife and assaulted Elizabeth Duris, occasioning her actual bodily harm, were withdrawn.
A prosecutor told the court that around 11.30pm on May 26, police were called to an alleged incident involving Duris and his mother. Officers initially arrested him under the Mental Health Act and were bringing him back to the station in a police car when he became increasingly violent. He made a comment: "Tick, tick, boom. I have hep (hepatitis) and Aids. I'll bite you."
The prosecutor said Duris then spat in an officer's face and on his uniform.
Defence barrister, Miss Heather Philips, said that on the night in question Duris had consumed quite a lot of prescription medication and behaved in an "unsavoury manner". She suggested the spitting was an "inadvertent splash" and said Duris had asked her to reiterate his apology. He was now the father of a five-week-old son living in Scotland and had undergone a course of drug and alcohol treatment. It had become apparent he had mental health issues and he was attending the Aisling Centre in Enniskillen.
Miss Philips said Duris had initially spent three weeks on remand in relation to this matter.
Deputy District Judge Paul Conway told Duris that Miss Philips had "said everything that possibly could be said to keep you out of jail".
However, he continued: "You spat at a police officer but made very cogent statements before spitting at him to have the officer fear as much as possible about what you were going to do."
He described Duris' criminal record, especially for offences against the police and violence in general, as "shocking", reminding him that he had been in prison on six occasions for assaulting and resisting police.
He concluded that there were no exceptional circumstances that would allow him to suspend the four-month jail sentence.