A HEARING about an alleged assault quickly escalated into a commotion at Murwillumbah court on Wednesday.

David James Grace, 36, of Murwillumbah, has pleaded not guilty to assault occasioning bodily harm.

Grace is accused of throwing a glass at pushbike rider Steven Murphy, splitting open his face and causing an injury requiring six stitches, at 11.55pm on April 20.

The incident occurred in front of the Riverview Hotel in South Murwillumbah.

"One (man) jumped in front of me, so I steered to the left of the footpath and onto the road," Mr Murphy said, while in the witness box this week.

"Then he started chasing me and I took off on the bike. I was hit by a glass about 5m away."

But Mr Grace's defence lawyer and ex-police prosecutor Russell Baxter argued while Mr Grace did exchange words with Mr Murphy, even chasing him a distance, he did not throw a glass.

Mr Grace was seen on CCTV in front of the hotel with a glass before the incident allegedly occurred, but Mr Murphy did not see Grace throw the glass as he was looking forward while riding.

What followed was an intense back and forth between Mr Baxter and police prosecutor Brett Gradisnik.

Murwillumbah police sergeant Paul Thierjung was called to provide evidence as a witness, after interviewing Grace at the scene of the alleged assault.

Mr Baxter asked Sgt Thierjung if he had spoken with anyone else apart from Grace regarding the incident.

The sergeant said he had not, because he had suspicions Grace was involved, running into him at the Riverview Hotel at 2.20am on April 21.

Witness Rebecca Foster said she did not remember being at the hotel at the time of the incident and said she thought she had left earlier, despite being seen on CCTV with Grace beforehand.

Magistrate Michael Dakin said he did not believe Ms Foster was telling the truth and he would consider a contempt charge if she continued to lie after recess. Ms Foster became upset and began to cry. The hearing continues.