A Perth man whose vehicle hit and killed the brother of former Dockers player Hayden Ballantyne as he used his mobile phone has been sentenced to seven months in prison.

Key points: Brendan Ballantyne was hit and killed by a car in September 2018

Brendan Ballantyne was hit and killed by a car in September 2018 The driver had crossed a solid white line and was doing 95 kph

The driver had crossed a solid white line and was doing 95 kph He admitted touching his phone to turn off the GPS

Brendan Ballantyne, 22, died in September 2018 after he was hit by a car being driven by Shaun David Milne in the Perth suburb of Waikiki.

The court heard Milne had reached over to touch his mobile phone before hitting Mr Ballantyne, who was walking alongside Ennis Avenue at night.

Mr Ballantyne was not walking in an authorised pedestrian zone but was on a "well-trodden" path, the court was told.

The driver had crossed the solid white line and was doing about 95 kilometres per hour.

Mr Ballantyne was hit from behind and suffered a fractured skull and fatal brain injury.

Brendan Ballantyne died after he was hit by a car while walking on a road in Perth's southern suburbs. ( Facebook )

Milne, a pizza delivery driver, had told police "I didn't see what I hit, it could have been a person, I'm not sure."

He admitted touching his phone to turn off the GPS.

When asked what caused the accident, Milne told police, "my stupidity".

The 48-year-old had pleaded guilty to careless driving causing death.

Cannabis in system 'not an aggravating factor'

The court heard he was "horrified" at what had happened, he didn't want to drive anymore and he thought about the deceased "every day".

Magistrate Matthew Walton said it was an "awful and devastating tragedy" caused by inattention while driving.

He told the court Milne had shown "unequivocal remorse."

While there was cannabis in Milne's system when the accident occurred, it was not considered an aggravating factor or cause.

Magistrate Walton said, however, "it is not an innocuous drug" and described Milne's use as "ridiculous and foolish".

The magistrate appeared to become emotional as he looked at relatives of Mr Ballantyne and told them that nothing he or the court did could compensate for the loss of a human life.

But relatives of Mr Ballantyne sitting in court expressed anger and frustration when the sentence was read out.

Victim had unborn child

The court heard Brendan Ballantyne had a fiance and two young children, including an infant who had not been born when he was killed.

Outside court, Hayden Ballantyne spoke about Brendan.

Hayden Ballantyne said he did not think the seven-month sentence was enough. ( AAP: Richard Wainwright )

"We lost Brendan on grand final night, 2018, and today, Shaun Milne got seven months for taking away our Brendan," he said.

"We don't think seven months is enough.

"We understand it's more that the weak system has let us down rather than the evidence presented, but we'll learn to deal with it.

"We won't forget Brendan."

As well as being sentenced to seven months in jail, Milne was fined $400 and disqualified from driving for six months.