West Australian Premier Colin Barnett has not ruled out the possibility of former treasurer Troy Buswell returning to Cabinet.

Mr Buswell's first day back at Parliament yesterday was dominated by questions about an incident on February 23, when he crashed his ministerial vehicle into several cars near his Subiaco home while returning home in the early hours from a wedding.

The Member for Vasse subsequently suffered a breakdown, took leave from Parliament and relinquished his Treasury and Transport portfolios.

Last week, he was fined more than $3,000 and banned from driving for 12 months after pleading guilty to 11 traffic charges.

The Premier says Mr Buswell is unlikely to return to the frontbench in the "immediate future" but has stopped short of ruling out a return altogether.

"I'm not going to put dates on it, at the moment," Mr Barnett said.

"Troy has just come back to work, he is still unwell, he's under medical care and I think his colleagues, particularly in the Liberal party, want to see him make a recovery.

"Who knows what can happen in 10 years' time, but there is no consideration for Troy returning to Cabinet and indeed he's made it very clear he has no desire to do so."

Buswell: 'Embarrassed' and 'mortified'

Yesterday, Mr Buswell apologised for the crashes and revealed he had been diagnosed with bipolar disorder and depression.

Mr Buswell said he was "embarrassed" and "mortified" by the events of 23 February.

"I accept responsibility for my actions. I pleaded guilty and I paid the fine and I have no more comment to make in relation to events surrounding those matters," he said.

However, he repeatedly refused to answer questions about whether he had been drinking on the night of the incident or why he had not participated in police interviews, saying he had employed a lawyer who had done so on his behalf.

West Australian Opposition Leader Mark McGowan said Mr Buswell should have answered questions about the incident.

"I don't think Mr Buswell's explanation was good enough," he said.

"The central question is how much did he drink before he drove home that evening and caused all of that damage and risked people's lives?"

The Premier said he had not asked Mr Buswell if he was drinking on the night of the crashes because it was not his job to investigate the incident.

"Be very clear leader of the Opposition, the issue of damage to the vehicle and damage to other vehicles was a matter, and is a matter, for police investigation," Mr Barnett said.