Last Valentine’s Day, Oscar Pistorius killed his girlfriend Reeva Steenkamp after firing four times through a locked bathroom door in the middle of the night. He thought Steenkamp was still in bed next to him. He thought she was an intruder, he said, offering up the flimsiest of defences for the indefensible. It was as if Pistorius knew he didn’t need to come up with a plausible explanation and so he did not even try.

Since the trial began in March, we’ve watched and waited and hoped for justice. It has been a bit surreal, given the facts of the case, to imagine an outcome where justice would not be served. Or it has been a bit surreal to accept that we live in a world where a man can justify shooting an unarmed woman through a locked door. Then again, this is also a world where an armed police officer can shoot an unarmed young black man. Whether in South Africa or Ferguson, Missouri, the rules most of us live by hardly seem to apply to white men.

Today, we have a clearer understanding of what justice means for certain groups of people, which is to say that justice can mean far too little. Judge Thokozile Matilda Masipa has found Pistorius guilty of culpable homicide rather than premeditated murder. Hers is a verdict that raises the question – what does a man have to do to be found guilty of murdering a woman?

Among her comments, Judge Masipa, who has acquitted herself well throughout the trial, noted that Pistorius’s defence of his crime can “reasonably possibly be true”. The evidence against Pistorius for premeditated murder was “purely circumstantial”. He did, however, act negligently because “a reasonable person with a similar disability would have foreseen that the person behind the door would be killed, and the accused failed to take action to avoid this”. Those words are hollow because a reasonable person never would have been in such a situation in the first place.

We might be able to say that this is a failure of prosecution, that the prosecutors did not do enough to prove that Pistorius committed premeditated murder. Those words feel flimsy right now. A woman is dead at the hands of her intimate partner. She is dead under the most implausible of circumstances because what would an intruder be doing, locked in a bathroom in the middle of the night? We know, because of details that emerged after she was killed, that Steenkamp and Pistorius had volatile moments in their relationship. We know Pistorius had a penchant for modern weaponry. We know a woman is dead, and still what we know is not enough.

Among the other counts Judge Masipa adjudicated, Pistorius was convicted of the negligent handling of a firearm after he misfired a gun in a restaurant last year. One cannot help but feel that interrupting a meal and interrupting a woman’s life are offences held in somewhat equal regard in this world. Now we will have to wait until 13 October for sentencing to find out what the judge sees as a fitting punishment for this lesser crime. That punishment, too, will not be enough.

What makes this all the more offensive is how Pistorius has, essentially, framed his defence as a fear of blackness. By evoking an unseen intruder he has exploited the complex and fraught racial history of South Africa to help justify his crime. As Margie Orford wrote, in these pages, “This imaginary body of the paranoid imaginings of suburban South Africa has lurked like a bogeyman at the periphery of this story for the past year. It is the threatening body, nameless and faceless, of an armed and dangerous black intruder.”

Pistorius would have us believe that he thought his girlfriend was safely in bed next to him. He would have us believe this mythical black intruder was locked in his bathroom. He would have us believe this mythical black intruder was whom he was killing when he fired through a closed door four times, as if somehow that would be justifiable. Though early this morning I may not understand this world we live in, Oscar Pistorius understands it and what he can get away with, perfectly.

• This article was amended on 16 September 2014 to correct the subheading. An earlier version had used invoked where evoked was meant.

