In its opinion, published on Friday, the court clarified that if a regulator, which includes the Law Society of Scotland and the Scottish Legal Complaints Commission, issues a solicitor with a statutory notice under the Legal Profession and Legal Aid (Scotland) Act 2007, a solicitor is obliged to provide information which is confidential.

The court reaffirmed, however, that there are no circumstances in which a regulator can access material which is covered by legal professional privilege.

Murray Etherington, Law Society of Scotland president, said: “The Court of Session has considered the concerns we raised around confidentiality. The opinion provides a clear direction on what is expected of solicitors in relation to third party complaints to ensure that they can be properly investigated. We are pleased that the intervention has upheld the importance of legal professional privilege.

“Following today’s opinion, we will review our guidance for our members.”

In a statement, the SLCC said: “This decision makes clear to the profession that a request from the SLCC for information is one they must comply with, including in cases where the complainer is not the client.

“Lawyers can do so in the knowledge that the court recognises the legislation setting up the SLCC overrides their duty of confidentiality. We can also reassure lawyers that the SLCC will act to protect client confidentiality in the way it handles such information, given the public interest in the SLCC being able to investigate complaints thoroughly and fairly.

“The court notes its earlier guidance that legally privileged material can only be shared with client consent.

“In most cases we expect that firms should be easily able to produce the required information, or that discussion with the SLCC will enable agreement on what needs to be provided to allow us to carry out our statutory role.”