Drug users should not be sent to prison for possession of illegal substances, Willie Rennie has said.

The Scottish Liberal Democrat leader told STV News' political editor Bernard Ponsonby he would remove the power to send drug users to jail from judges.

Rennie said: "What we should do is follow the system in Portugal. The system in Portugal is that there is a process of penalties through drug commissions.

"For instance if you are caught with drugs in possession, small enough amounts for possession purposes rather than dealing - if you are dealing you go to jail, that is quite clear. If you are in possession what you do is you go before this commission and they impose a penalty which is rehabilitation.

"If you do not comply with that penalty of rehabilitation you could go to jail but it is only in those circumstances which you could go to jail".

Asked if he would remove the power of judges to send those in possession to jail, Rennie replied: "Yes."

He explained that he favours an "enlightened approach" when it comes to tackling the issue of illegal substances.

The Lib Dem leader's interview came on the same day a probe into the party's only Scottish MP Alistair Carmichael was dropped.

Carmichael admitted to lying about his role in the leaking of a government document about First Minister Nicola Sturgeon from his department in 2015.

Rennie, who donated £750 to Carmichael's legal fees, was asked if he would vote for a liar.

He said: "Look, Alistair recognised he made a mistake. I think we are moving on from that."

When asked again, Rennie answered: "I would vote for Alistair there is no doubt because Alistair is an excellent member of parliament who stood up for his constituency for 14 years".

The party's manifesto supports a 1p rise across all income tax rates to fund extra spending on education.

When combined with the planned rise in the personal allowance by the UK Government, the party claims you would have to earn £21,501 to be worse off under their proposals. Rennie was asked if those who earn that sort of salary consider themselves well off.

Rennie answered: "No, of course not. We are not asking a huge amount from them, it's a very small amount that we are asking them to pay over the course of a year. For instance someone on a medium wage of £23,700 will pay something like £27 per year more".

The Lib Dem leader also emphasised those earners will benefit from improved public services funded through the taxation.

With two weeks of campaigning left Rennie believes that party "will grow" at the election.

Election Face to Face features party leaders in the Holyrood elections being interviewed by STV News Political Editor Bernard Ponsonby:

It is screened on STV Glasgow and STV Edinburgh at 8.30pm and then on Scotland Tonight on STV at 10.30pm.