The 16-year-old girl came in contact with the man through a sadomasochism-themed website and later signed a “slave contract” in which she consented to being “used, abused and thoroughly humiliated”.

“I want to have a really hard master. Someone who won’t wimp out,” the teen wrote the 32-year-old during their online chat, according to the Aftonbladet newspaper.

During their sexual encounter, which took place in January, the girl allowed herself to be locked in a cage and have clamps attached to her breasts, according to several media reports.

The 16-year-old was also hit with whips and rulers, and made to have oral sex until she vomited, according to Aftonbladet.

Police were alerted to the alleged assault when a relative of the teen noticed she had bruises all over her body.

The issue of how much sexual violence is allowed between consensual sex partners has never been heard in the Swedish court system and experts in sadomasochism are expected to be called to testify in the hearing in Malmö district court.

“What I want to establish is that even if they say they are in agreement over this then you not allowed to seriously assault someone,” prosecutor Ulrika Rogland told the local Sydsvenskan daily in June when charges were originally filed.

It is on this issue that the district court has to issue a ruling, is this aggravated assault and was she able to agree to it?”

In her opening statements on Monday, Rogland claimed the girl’s consent to the violent sex should be nullified because the man was aware that she was prone to self-harming behaviour, according to Sydsvenskan.

However the man’s attorney,Bo Peterson, claimed that while the 32-year-old knew of the girl’s behaviour, he thought had outgrown it.

The prosecutor then showed pictures of the girl’s arms featuring several deep cuts and argued that there was no way to man could have avoid seeing the wounds.

The 32-year-old told the court that he had been involved in similar sex role-play games for several years and considers himself capable of assessing whether or not people really want to do what they say they want to do.

When the girl arrived at his apartment they discussed anal sex, among other things, as well as what word they would use to signal to the other to stop their activities if the pain became to great.

“I pinched her nipples to feel if it was OK,” the man said.

He and his attorney brought several whips and other sex toys to illustrate what is considered normal within the world of BDSM, Body Discipline Sado Masochism.

The 32-year-old held up a ruler to show how someone “warms-up” the body by hitting it lightly, making a slapping sound which echoed throughout the courtroom.

“I can tell if it’s going to cause a bruise or not,” he told the court and went on to explain what the girl has said she wanted when the two of them met.