The victim was was slashed across the face in a suspected knife attack after making offensive remarks to women, the High Court in Belfast has been told.
He underwent surgery for the wounds inflicted outside a house following a heavy drinking session at Derry city centre bar.
Prosecutors said he was cut from under his ear to the corner of his mouth in the early hours of December 9.
His alleged attacker, John Stokes from Belfast faces charges of grievous bodily harm with intent and possession of a blade in public. He claims it was a pre-emptive strike in self defence.
He was granted bail but banned from going anywhere in the North west of the River Bann.
Stokes and the injured man, from Letterkenny, drank 12-15 bottles of beer each during a night out with others, the court was told.
After the bar closed they went back to a house in Strathfoyle where more drink was taken.
A prosecuting lawyer told the hearing that Stokes allegedly asked the stab victim to step outside after he made comments some women at the house had found offensive.
It was claimed that as they stood smoking and chatting Stokes suddenly slashed him across his cheek.
Stokes claimed, however, that it was the injured man who came at him with a blade.
The court heard he then lashed out with a broken bottle on realising he was about to be attacked.
Lord Justice Girvan granted bail but banned Stokes from going any further than Toome.