The Paralympic sprinter stands accused of the premeditated murder of Reeva Steenkamp in his home on February 14, 2013. He also faces a gun charge related to the killing, along with two additional gun-related charges for two separate instances of firing a gun in a public space before the killing.
What's the difference between the rules of a trial in South Africa and those in the United States? CNN's Chris Cuomo explains in the video above.
South Africa abolished jury trials in 1969, while the country was under apartheid, due to fears of racial prejudice by white jurors. Pistorius will be tried in a high court in Pretoria by Thokozile Matilda Masipa - the second black woman appointed to the bench since apartheid ended
There's no hard timeline but it's expected to last about three weeks.
For premeditated murder, the mandatory sentence in South Africa is a life sentence, which in practice is 25 years unless someone can prove extraordinary circumstances.
Extraordinary circumstances could include a combination of number of factors: for example, that it was a first offense, the age of the person and in Pistorius' case, his disability and the impact this could have had on his actions.
However, legal expert James Grant said if the court accepted the prosecution's case - that Pistorius chased Steenkamp into the bathroom and "hunted" her down - the track star's defense team would be hard-pressed to convince the court that there should be any considerations that should override the repugnance that should be felt.
If Pistorius is found not guilty, he would face a "competent verdict" or lesser charge of culpable homicide, which is based on negligence.
Pistorius is not claiming self-defense; he is claiming to have been mistaken about his need for self-defense. He is denying that he intentionally unlawfully killed Steenkamp.
Grant said the defense boiled down to Pistorius saying "I made a mistake."
If the court were to rule that the mistake was unreasonable - based on what an objective, ordinary South African would do in the circumstances of the accused - he would be found guilty of culpable homicide.
Grant said he would expect a court to probably conclude that it is unreasonable to fire at anybody through a closed door regardless of whether they were an intruder, because of the value of human life.
"I'm expecting that if he beats the murder charge, he is in very grave jeopardy of being convicted of culpable homicide," he said.
What about appeals?
If Pistorius is convicted, he could potentially appeal to the supreme court and even eventually to South Africa's constitutional court.
If the initial court did not give him leave to appeal, he could petition South Africa's chief justice for permission.
The right to appeal depends on whether, based on the facts of the case, the initial judge or magistrate believes a different court could possibly reach a different verdict.
South Africa's highest court, the constitutional court, used to be only for cases regarding constitutional matters, but a recent act of parliament broadened its remit.
The murder trial of Oscar Pistorius opened Monday with chilling testimony from the South African amputee track star's neighbor, who described "bloodcurdling screams" coming from next door, followed by gunshots, the night of Reeva Steenkamp's death last year.
"Something terrible was happening at that house," Michelle Burger testified.
She told the court that she heard a woman's screams and a man screaming for help.
"Just after 3, I woke up from a woman's terrible screams," she said. "Then I also heard a man screaming for help. Three times he yelled for help."
Burger said her husband called authorities. She later told her husband that she feared the woman had witnessed her husband being shot "because after he screamed, we didn't hear him."
Language issues caused problems after the lunch break, as defense attorney Barry Roux pressed Burger on her account during cross-examination.
She frequently had to help her Afrikaans interpreter translate her words into English, and eventually dropped speaking in her native tongue altogether.
Roux questioned Burger's timeline of events and what she heard, asking if the "bang" sounds she heard might not have been gunshots, but rather a cricket bat bashing at the bathroom door.
She answered that she had clearly heard gunshots, testily answering Roux's questions about timing, saying she "didn't sit there with a stopwatch and take down the timing of each shot."
A short time before her testimony, Pistorius pleaded not guilty to murdering Steenkamp, his girlfriend, inside his house a year ago. He also pleaded not guilty to several weapons-related charges.
It's expected to take about three weeks for a judge to hear both sides and decide whether Pistorius mistook Steenkamp for a burglar, as he says, or killed her in cold blood.
Parts of Pistorius' trial are being televised live - a first in South Africa - after a judge's decision last week allowing cameras in the courtroom. But any testimony by Pistorius, or witnesses who do not consent, will not be televised.
June Steenkamp is inside the courtroom, marking the first time she has faced her daughter's killer in court. Reeva's parents have avoided previous court appearances because, they said, they wanted privacy. Pistorius' brother and sister were also present for Monday's proceedings, which were delayed by an hour and a half because of pretrial "hiccups," Judge Thokozile Matilda Masipa said.
With the aid of two assessors who will help her evaluate the facts of the case, Masipa - only the second black woman appointed to the bench since the end of apartheid - will determine Pistorius' fate. South Africa abolished jury trials in 1969.
A few minutes before the trial's scheduled start at 10 a.m. (3 a.m. ET), Pistorius arrived at the Pretoria High Court through a back door, avoiding a massive media circus assembled in front.
Pistorius faces one charge of premeditated murder and a firearms charge associated with Steenkamp's killing, as well as two separate gun indictments from previous incidents. In South Africa, premeditated murder carries a mandatory life sentence, with a minimum of 25 years. He also could get five years for each gun indictment and 15 years for the firearms charge.
If he isn't convicted of premeditated murder, the sprinter would face a lesser charge of "culpable homicide," a crime based on negligence, and could be looking at up to 15 years on that charge, experts say.
Pistorius, 27, and Steenkamp, 29, were a young, attractive and high-profile couple who were popular in South Africa's social circles. The "Blade Runner" won six Paralympic gold medals and became the first double amputee runner to compete in the 2012 Summer Olympics in London. Cover girl Steenkamp, who was soon to star in a TV reality show, was on the cusp of becoming a celebrity in her own right.
Everything changed before dawn on Valentine's Day 2013, as Steenkamp lay lifeless in a pool of blood on the floor of her boyfriend's house in an upscale gated community in Pretoria. Moments before, Pistorius says, he had pointed his 9 mm pistol toward an upstairs toilet room and fired four bullets through the locked door.
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