The UK will back the Scottish government over plans to bring in a minimum price for alcohol, according to the Advocate General for Scotland.
The new law, designed to tackle alcohol misuse by setting a floor price of 50p per unit, is being challenged at the Court of Session by the Scotch Whisky Association.
The European Commission has also raised concerns about the legality of the legislation and its compatibility with EU law on free trade.
The advocate general, Lord Wallace of Tankerness QC, a former leader of the Liberal Democrats, will discuss the UK government's position at a legal conference at the University of Edinburgh on Tuesday.
The UK government plans to follow suit with minimum prices for alcohol, beginning with a consultation on introducing minimum pricing in England and Wales.
Lord Wallace is expected to tell the conference: "I am sure we are all conscious of the great problems that alcohol causes for countless people in Scotland every year. In light of this, my party supported the Scottish government's proposals for the introduction of a minimum price for alcohol and, indeed, the UK government will shortly be consulting on the introduction of minimum pricing in England and Wales.
"The proposal for England and Wales has the backing of the Royal College of Physicians and the Association of Chief Police Officers and could mean 50,000 fewer crimes and around 900 fewer alcohol-related deaths per year in England and Wales by the end of this decade.
"It would be open to the UK government to sit on the sidelines and watch while the Scottish Government seeks to fend off these challenges. But we will not do that.
"When the case is first heard in the Court of Session later this month the UK government will be standing shoulder to shoulder with the Scottish government, seeking to support and complement the arguments that they present and, in particular, ensure that the court has the benefit of the UK Government's experience and expertise in EU law."
A 50p minimum price would take the cost of a 70cl bottle of 37.5% vodka to no less than £13.13, four 440ml cans of 9% lager would increase to a minimum of £7.92 and a 75cl bottle of 12.5% wine could be sold for no less than £4.69, the Scottish government said.
Research by Sheffield University has indicated that setting the minimum price at 50p would lead to 60 fewer deaths, 1,600 fewer hospital admissions and 3,500 fewer crimes in its first year.
After 10 years there could be 300 fewer deaths annually, 6,500 fewer hospital admissions and overall savings worth £942 million.
The Scottish Government says it will fight any legal challenges to the legislation.