A BOY was freed on bail seven times before he allegedly used a box-cutter to inflict horrific injuries on a young father and his pregnant wife in their Melbourne home on Christmas Eve.

The 13-year-old has been charged after the man was slashed from the back of his head to his nose in front of his toddler son.

His pregnant wife was also allegedly kicked in the attack and suffered a severe head wound from the box-cutter, with both parents expected to be left scarred for life.

The boy, who is alleged to have attacked the western suburbs couple, had been granted bail seven times despite facing more than 60 outstanding charges including arson, armed robbery, robbery and aggravated burglary.

Police Association secretary Sen-Sgt Greg Davies said the law governing bail for young offenders needed to be changed.

"Until the community decides their rights are more important than the rights of one individual, no matter what his age is, this sort of thing is just going to keep happening, so get outraged or get used to it," he said.

Government spokeswoman Kate Walshe said the Government was considering a range of options to strengthen bail laws "and will consult with Victoria Police on any specific problems police are encountering".

The victims were at their western suburbs home on Christmas Eve when the father noticed the boy lurking in the kitchen.

The pair grappled moments later and the 13-year-old allegedly used the box-cutter to slash the man from the back of his head to his nose.

The father lost a litre of blood in the attack, which he feared would kill him.

His seven-month pregnant wife tried to intervene but also reportedly suffered a severe head wound from the box-cutter.

She was allegedly kicked in the stomach after being knocked to the floor during the violence.

The husband then used a kitchen knife to stab the intruder, who ran from the property.

He was arrested moments later by police who had been called to the area after a separate confrontation in which the boy allegedly pulled a knife on a nearby resident.

The alleged offender - who the Herald Sun cannot name because of his age - remains in hospital recovering from the knife wounds.

Detectives from Maribyrnong CIU charged the boy with aggravated burglary, intentionally causing serious injury and assault.

He was remanded in custody to appear at a Children's Court this month.

Sen-Sgt Davies said that under existing laws a person aged under 14 is presumed not to know the difference between right or wrong.

"So the police have got to prove this kid knows the difference between right or wrong before they can get a conviction," he said.

"These laws were written for a different time in history. A 13-year-old today is very, very different than a 13-year-old from the 1940s or '50s.

"These kids know they're going to get a slap on the wrist, they know they're going to get bail, they know they'll be home by the end of the day. They even know when it gets to court they'll be slapped on the wrist with a wet lettuce leaf.

"There is no reason for them to behave in the way that they should behave, and until the community demands that their government protect them from these people and realise that their rights are more important than those of one individual then get used to it, because this is a glimpse into the future."

mark.buttler@news.com.au