THE Lord Advocate was the last known unknown.

We know the Scottish Government wants to establish safer drug consumption facilities in Glasgow. We know the local authority and NHS support them. We know there is a majority in Holyrood in favour of such a policy. We also know that the UK Government has set its face against prioritising public health approaches to drug use.

But until Monday, we didn’t know exactly where Dorothy Bain KC stood. As Lord Advocate, she’s already made some promising moves on drugs policy, extending powers to give recorded police warnings to people caught in possession of Class A substances early on in her tenure.

The National:

READ MORE: How do safe drug consumption rooms work?

But could she be persuaded to adopt a prosecution policy that anyone using these public health facilities wouldn’t face arrest and prosecution?

Her predecessor threw out a blizzard of legal detail to explain why he wasn’t prepared to give legal reassurances to drugs workers and service users they wouldn’t be prosecuted. He pointed out – correctly in legal terms – that possession of controlled drugs is a criminal offence under the Misuse of Drugs Act 1971 which anyone bringing heroin into the facility would be committing.

For months, Bain has remained inscrutable – as the UK Government worked hard to close down alternative ways of establishing safer drugs consumption facilities.

The simplest way to set up these facilities has always been with a Home Office licence – but even proposals for a pilot scheme were summarily rebuffed.

When that policy was backed by Westminster’s Home Affairs Committee two weeks ago, Suella Braverman’s department instantly published a press release saying they weren’t prepared even to contemplate the idea.

The National: Home Secretary Suella Braverman (Peter Byrne/PA)

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It looked like yet another constitutional stalemate in Scottish politics. Because the Misuse of Drugs Act is reserved to Westminster, Holyrood can’t unilaterally change the law. Because the Lord Advocate sets prosecution policy independently of politicians, she couldn’t just be directed by MSPs or the Scottish Government to produce a comfort letter confirming such a facility wouldn’t be raided by the police.

As Dorothy Bain stresses in her letter to MSPs, “prosecution policy is for me alone to set.” That goes for both the UK and Scottish governments. Prosecutors don’t make laws. But as chief public prosecutor, she has the authority to decide how the law is enforced – and where the public interest lies in enforcing it.

This left Bain as the only actor in Scotland with any legal initiative to clear the way for – or completely stymie – these innovations designed to prevent overdoses and reduce unnecessary drugs deaths.

This decision finally breaks the legal impasse. But it’s conditional. “Central to my consideration”, she says, “has been the fact that the proposed facility would be co-located with other services which, taken together, may be able to offer a range of support and assistance to those consuming drugs.”

She also highlights the importance of “proactive community engagement” and – because the scheme is a pilot – anticipates “careful and rigorous evaluation of the facility and its effects.”

Notwithstanding these reasonable caveats – this is a huge leap forward.