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.
Track star Oscar Pistorius broke down in court Thursday, the fourth day of his murder trial, as a neighbor described the grisly scenes when he tried to save the athlete's girlfriend after a fatal shooting on Valentine's Day 2013.
The amputee sprinter, 27, nicknamed "Blade Runner," has pleaded not guilty to all four counts against him, saying the killing of modelReeva Steenkamp, 29, was a tragic error and he mistook her for an intruder.
In graphic testimony, witness Johan Stipp, a doctor who lived close by, said he went to Pistorius' residence after hearing shots fired. He said he saw Steenkamp mortally wounded, her brain tissue mixed with blood and Pistorius praying for her to live.
"I remember the first thing he said when I got there was, 'I shot her, I thought she was a burglar and I shot her,' " Stipp told the court in Pretoria.
He said he had arrived and found Steenkamp's body lying at the bottom of the stairs. Pistorius was bent over her body with his left hand over her right groin and two fingers of his right hand in her mouth as he tried to clear her airway.
Stipp tried to assist and said he found no signs of pulse in her neck, no peripheral pulse nor breathing movements.
As the doctor described the details of her injuries to the court, Pistorius broke down with his head in his hands. He was also seen convulsing but then recovered and wiped his face and nose with a handkerchief.
Stipp, who said he had trained in the army with assault rifles and 9 mm pistols - the gun that killed Steenkamp - said he had been surprised to hear no ambulance had been called when he arrived. He left after it did.
Lawyers are battling over whether the world-famous athlete killed his girlfriend on purpose or by mistake when he fired four bullets through a closed bathroom door at her.
He wanted her to live'
Stipp told the court he did not realize Pistorius lived in the house until the day after the shooting when his wife told him.
The doctor was later cross-examined by defense attorney Barry Roux, who has been working toward establishing that Pistorius was the one heard screaming after the shots were fired.
Roux said he had consulted three specialists and the autopsy and asked Stipp: "That person after the shots would not have been able to scream. That person would be nonresponsive, does that make sense to you as a medical doctor?"
"It does," Stipp replied.
The prosecution interjected, saying Steenkamp could have screamed after the first shot. Earlier in the week, prosecutor Gerrie Nel, reading a report from an expert, told the court that of the four bullets fired toward Steenkamp "the fourth bullet hit her in the head. She then died."
Pistorius sat impassively during the exchange between Roux and Stipp. He leaned forward, his head down in his hand, as his attorney asked Stipp if the athlete had wanted Steenkamp to live.
"He definitely wanted her to live, yes," Stipp replied. "He looked sincere to me. He was crying; there were tears on his face."
After the court adjourned for the day Thursday, Pistorius was in tears as his sister consoled him.
Witness grilled over notes
Earlier Roux had cross-examined another neighbor who testified that he heard shouting from Pistorius' house before the shooting.
Charl Johnson, husband of the trial's first witness, was back on the stand after the defense team wanted to retrieve notes he had taken in the weeks after the shooting. Roux grilled Johnson about the notes such as "the screams did not sound like fighting but more like the panic and distress calls of being attacked."
Roux established that Johnson and his wife, Michelle Burger, thought they were hearing noise from a house break-in and not from an act of domestic violence. Nel said Roux was taking individual sentences out of context.
Johnson also testified he owns the same caliber gun as the one that killed Steenkamp and he has fired a firearm before and knows what it sounds like. When Roux asked if he has heard it from the distance of one house to another, he said did not have a similar experience to relate it to but was convinced he knew what the noise sounds like regardless of distance.
See more at CNN.com.
Tim Tesseneer was driving along Daytona Beach on Tuesday with his wife when they noticed the minivan driving through shallow water as it headed south.
That was unusual enough. But then they heard the screams. It was two children crying and waving for help out one of the rear windows.
Tesseneer threw the car in park and raced over to see whether he could get the children out of the minivan.
One child was screaming, Tesseneer recalled Wednesday to CNN's Piers Morgan. "Please help us, our mom is trying to kill us."
The other child he could see was wrestling a woman for the steering wheel.
But the woman just kept saying, "We're OK. We're OK. We're OK," as another man joined Tesseneer trying to get the driver to stop.
Then she mashed the accelerator, turned left and shot into the cold, heavy surf of the Atlantic Ocean touching the shore of the Florida city.
It was now a battle against the pull of the water, and the second man, Stacy Robinson, opened a door and pulled out the two panicked children.
There was a good chance if he and Tesseneer hadn't been there, the children, ages 10 and 9, would have drowned inside the van as it pitched in the water, officials said.
"I have siblings their age, so it was like the big brother came out in me," Robinson said.
But there was one more child, a 3-year-old girl strapped in a car seat. A lifeguard dove in through a front window and unbuckled the child and handed her to another lifeguard. The vehicle was bobbing in water about 3 feet deep.
The mother just walked away, Tesseneer said, silent with a strange, almost "possessed" look on her face.
A day later she was at a hospital in Daytona Beach awaiting a mental evaluation, Volusia County Sheriff Ben Johnson said. Her children, including her unborn baby, were fine.
No charges had been filed, Johnson said, as the investigation into why she drove into the ocean was just beginning.
CNN is not identifying the children or the woman, who was stopped earlier in the day after her sister called police to let them know how concerned she was for her sibling's mental state.
According to a Daytona Beach Police report, the woman was stopped by an officer, who questioned her. In the back seat the kids sat calmly with smiles. The woman told an officer that she feared for her safety and was worried her former husband would harm them.
But the officer was concerned that she might have a mental illness. He asked a detective who was there to talk to her while other officers called the sister back.
In the report, the officer writes of discussing the woman's behavior with the detective.
They came to the same conclusion; she couldn't be held under a Florida law that allows for detention of people believed to be impaired by mental illness and who possibly pose a risk of harm.
They told her she could go; one officer followed her for a short time.
Almost two hours later, she was driving on the beach, outside the traffic lane, drawing the attention of beach patrol and bystanders like Robinson and Tesseneer, on vacation from North Carolina.
Sheriff Johnson said the children are now in the state's care. They had been interviewed by detectives from his agency, which was taking the lead because it has more investigators than other departments.
The woman had yet to speak with detectives.
Johnson said his team will try to determine whether this was a criminal act or one that resulted from a medical issue.
No one in his department knows how long the woman had been in town or why she was visiting from South Carolina. She did have family in the area, the sheriff said.
One of New York City's most exclusive restaurants is in a real pickle after being served a "C" grade by the New York City Department of Health.
The restaurant, Per Se, was slammed by health inspectors after racking up 42 violation points during its inspection on February 19, city health department records showed.
Per Se, one of only seven in New York City to earn three Michelin stars, previously had an "A" rating before the inspection.
Violations listed in the latest health inspection included no hand-washing facility or soap in the food-prep area, hot and cold items held in improper temperatures, and eating or drinking in the food-prep area and tobacco use, all of which qualify as "critical" violations, according to the records.
In its last inspection in June 2013, Per Se had only one violation worth 7 points, but previous inspections in 2013 and 2011 also fell into the 40-point range.
Inspectors give an "A" for 0 to 13 points, "B" for 14 to 27 points and "C" for 28 or more, according to the health department's website.