Ex-principal denies child sex offences

The former principal of a private school south of Perth who is charged with historic child sex offences is denying the allegations, saying the incidents simply never happened.

Matthew Edward Faulkner, 54, is accused of committing indecent acts against a Catholic school student, who he taught in years four and six, and the friend of his foster child.

Among the student's allegations are that Faulkner stuck his hand down the back of his pants and hit him on the bare bottom with a ruler in 1997.

Defence lawyer Phil Urquhart says there are two sides to every story.

"His defence is simple. He did not commit any of these charges," Mr Urquhart told the West Australian District Court in opening submissions for Faulkner's trial on Monday.

"They did not happen."

He says his client is in a difficult position, given the offences are alleged to have occurred long ago when Faulkner was in his 20s and 30s.

Mr Urquhart said there had been occasions when he had allowed the foster child and his friend to smoke cigarettes and drink alcohol.

On rare occasions, he had allowed them to smoke cannabis.

And the friend had been present along with other teenage boys when Faulkner held a party where a stripper had been hired.

But it was not a trial of moral issues.

"You will hear evidence that will cast him in a less than favourable light," Mr Urquhart told the jury.

"Keep an open mind. Don't form any conclusions until you have heard all the evidence."

The trial continues.