The cost of Scotland's methadone programme could be as high as £60m, the Scottish Tory conference heard.
And most addicts who use the heroin substitute do not end up coming off the drug, said drug abuse expert Neil McKeganey of, Glasgow University.
Speaking during a debate on justice, Prof McKeganey said Scotland's drugs problem was one of the worst in Europe.
"The statistics are truly shocking," he claimed, as he said it cost up to £2,800 a year to maintain an addict on methadone.
Demand for police services is "almost overwhelming", the Scottish Police Federation's Joe Grant told the conference.
He said dealing with terrorism, sex offenders and other legislative requirements took up vast numbers of officers.
Meanwhile, Graeme Pearson, former head of the Scottish Crime and Drug Enforcement Agency, warned that organised crime, on a par with Italy and Columbia, could gain a foothold in Scotland.
And Scottish Tory justice spokesman Bill Aitken said the independence of judges was under threat from the SNP's "soft-touch" approach to sentencing.
Scottish Tory leader Annabel Goldie turned biker as she roared round Ayr racecourse on a Harley Davidson motorcycle, describing the experience as "thrilling".
She took the opportunity to raise cash for charity as the conference venue also played host to a gathering of biking enthusiasts.
She donned a crash helmet to ride pillion on a Harley trike, joined by a cavalcade of other bikes.
She declared: "I must say - David Cameron earlier today, then a ride on a Harley later on. By Jove, that's some day."
Moves to change the Act of Settlement would damage the monarchy and lead to the break-up of the Commonwealth, a Tory claimed.
Philip Lardner said the legislation, which bars Roman Catholics from the throne and also ensures the male succession, ensured British interests were put first for 300 years.
"I believe our country deserves a sovereign head of state whose sole loyalty is to his, or her, people and not to some foreign, religious or political figurehead," Mr Lardner said.
He later denied this could be seen as anti-Catholic.