The former N-Dubz star was convicted of common assault for hitting celebrity blogger Savvas Morgan in the face at V Festival in Chelmsford in August, 2013, leaving him with a swollen left eye.
In a bid to clear her name, a year on, Tulisa, 26, launched an appeal, which started on Monday.
Despite Tulisa denying hitting Morgan, claiming they had a verbal disagreement after a long-running spat, a district judge dismissed her account and convicted her of assault last year.
Tuesday morning, the former X Factor judge appeared in Snaresbrook Crown Court in London to appeal against the conviction.
Her defence barrister, Simon Gledhill, told the hearing that Morgan had bullied the singer following a clash in a London nightclub in 2011.
It is alleged that Tulisa has held a ‘grudge’ against Morgan after he published a link to her sex tape, which was leaked by her ex-boyfriend Justin Edwards in 2012.
Prosecutor Matthew McNiff maintained the assault allegation is correct and insisted Tulisa "punched Morgan to the right eye" when they clashed at the festival.
Morgan reportedly suffered swelling for up to 48 hours after the assault.
We will update you with more news from the hearing as it continues.