The Scottish government has pressed ahead with the change despite calls from GPs and medico-legal organisations not to follow the example set by England's Lord Chancellor, who cut the discount rate from 2.5 to minus 0.75 earlier this year.
Medical defence organisations have warned the change will have a catastrophic impact on the cost of GP indemnity, which has already risen sharply in recent years.
Updated legislation to implement the new discount rate was laid before the Scottish parliament on Monday and takes effect today.
MDDUS chief executive Chris Kenny said: 'Today’s reduction in the discount rate is good news for lawyers, but bad news for the NHS. It adds avoidable pressure on NHS resources and doctors’ and dentists’ subscriptions to medical defence organisations.
'It is disappointing that Scottish ministers have chosen to follow their English counterparts in this potentially legally flawed decision, particularly when consultation on an improved system in England is expected in a matter of days. We will be seeking urgent assurances from Scottish ministers about their plans for improvement, and how they plan to tackle the funding consequences for the NHS in Scotland and our members.'
Dr Hugh Stewart, MDU director of legal services and Scottish affairs, said: 'The Scottish government has, overnight, increased the cost of claims against GPs, some of which may now double in cost. Although GPs treat NHS patients, they pay for their own indemnity against claims and must be protected against the inevitable increase in indemnity costs that this change in the law will cause.
'We are considering the impact of this decision carefully and will seek to work with the Scottish health and social care directorate to find a solution to protect our GP members.'
MPS chief executive Simon Kayll said: 'We are extremely disappointed and concerned by the Scottish government’s decision to follow England and Wales and reduce the personal injury discount rate so dramatically. A rate of -0.75% is unsustainable. Without sufficient support from government for GPs, this decision will significantly increase the cost of settling future loss claims against the NHS and our members in Scotland at a time when the cost of clinical negligence is already at a worryingly high level.'
GPC Scotland chair Dr Alan McDevitt warned earlier this month at the Scottish LMCs conference that it would not be fair to expect GPs to bear the extra cost of the updated rate, which will inflate the value of personal injury payouts.
He said the BMA had been clear with the Scottish government that it would expect GPs' costs to be covered through contract funding. Dr McDevitt also told LMCs this month that the current situation around indemnity was not sustainable and that a 'significant change' was needed to stop GPs quitting the profession.