A father and son have denied setting a trap to catch a group of teenage gangsters outside their Canberra home last year.

On Tuesday the jury will be asked to decide whether 49-year-old Andrew Jay Hogan and his 19-year-old son Sebastian Lewis Hogan are guilty of assault and illegal confinement, or whether they were acting in self-defence and making a citizens' arrest.

The court heard that Sebastian Hogan's car had been vandalised a number of times and that threatening messages were sent to his phone.

Jurors heard he believed a local gang known as One Life was responsible for the threats and replied to a text message challenging one of the group to meet him outside his family home.

It is alleged the Hogans armed themselves and waited in the dark outside their home in Tuggeranong to ambush the gang.

The court heard that when four men showed up, armed with a baseball bat and an empty rifle, the father and son allegedly assaulted two of the group and tied them up on the front lawn before calling police.

The crown prosecutor has described their actions as vigilantism.

But the men's defence lawyers have argued the two were simply protecting their family and their home.