"The community needs to be told that when you've driven drunk there will be no escaping years and years of jail," District Court Judge Ian McClintock said in sentencing Jarad Michael Smith, 23, on Friday.

"That message is particularly relevant at this time of year.

"Two lives have been lost in utterly unnecessary and catastrophic circumstances. The tragedy is all the more poignant because it could have been avoided."

The message was echoed by the sister of one of Smith's victims who tearfully declared outside court: "Please, do not get in a car and drink and drive".

Judge McClintock said that Smith had a blood alcohol level of .201 and was affected by MDMA and cocaine when his car mounted the footpath on Victoria Road, Rozelle, and ploughed into Catherine Pracy, 47 and her partner Gary Kelley, 49, on December 14 last year.

Ms Pracy died instantly, while Mr Kelley died at hospital later that day.

The court heard the young carpenter had only just left his work Christmas party when he had made the inexplicable decision to drive despite consuming beer, vodka shots, two lines of cocaine and a drink which he thought had been spiked with the drug "ice" but had in fact contained MDMA.

"I've no doubt that he fell asleep a few moments later when he turned on Victoria Road and shortly before the accident," Judge McClintock said.

When Smith realised what had happened, he stopped and got out of his ute but then fled the scene, pursued by a bystander.

Eventually the pursuer found Smith huddled behind a row of tall pot plants in a backyard not far from the scene and called the police who arrested him.

"I'm sorry, I'm sorry … I know, I f---ed up – I hit them," Smith reportedly told the first police on the scene.

"I took too much ice; I thought it was cocaine."

Smith subsequently pleaded guilty to two counts of aggravated driving occasioning death, and admitted to one count of failing to stop and assist, which was taken into account on his sentencing.

Judge McClintock was scathingly critical, not only of the P-plater, but of the other people at Smith's work Christmas party who allowed him to continue drinking, and then to drive.

"It must have been known to his companions that he was incapable of driving a motor vehicle, but no attempt was made to stop him from doing so," he said.

"Alcohol was available well into the morning and available to the offender when it shouldn't have been."

He found that Smith was "profoundly remorseful" about what he had done, avoiding the "cliches" of contrition that were often expressed in courtrooms.

"I wish I had died instead of the victims." Smith had declared.

This remorse, in conjunction with Smith's strong prospects for rehabilitation, early guilty plea and lack of prior offences, resulted in a significant reduction in the young man's sentence.

Nevertheless, the 23-year-old's family appeared devastated by the result, weeping openly in the courtroom as the judge indicated the maximum sentence of seven years with a minimum non-parole period of four years.

Speaking outside court, Ms Pracy's sister Louise Miller said the entire country needed "a big wake-up call".

"Change the system," Ms Miller said.

"We need people to be more responsible. My sister's life … She was a beautiful, beautiful person. This day should never have happened."