The lawyer and a paralegal twice took the pair into the cells at the High Court in Edinburgh, against the rules, earlier this year, it is claimed.
The lawyer allegedly told G4S staff that the two were there on work experience. G4S has ramped up security following the incidents. The firm, which has a contract to provide prisoner transport across Scotland, as well as security at several courts, has referred the advocate to police as well as the Scottish Prison Service (SPS), The Scotsman understands.
The prisoner was in court about eight weeks ago to appeal against a sentence. The case was delayed for a couple of days and then recalled and, on both occasions, his brother and sister were brought to visit.
The Scottish Legal Complaints Commission is also investigating, and the Faculty of Advocates is aware of the incidents. A source said the breaches had highlighted poor security levels at the High Court.
“The problem for G4S is that they were not asking anyone for ID so they are wide open to being fined,” he said. “If they had a system where everyone was asked, then it should not have happened, but they worked on the basis that no unauthorised persons ever tried to get in.”
He added: “Security has been tightened up now.”
The source said security at the High Court in Glasgow, which is also the responsibility of G4S, had been implemented with a similarly light touch.
In the cells, the prisoners are separated from their representatives by a thick glass screen. It is possible to pass a piece of paper or a pen between them, but not much else.
The breach only came to light when the man was taken back to prison in a G4S van and admitted to staff that his brother and sister had been among visitors.
It remains to be seen what action the legal profession will take. But the source said: “James Wolffe QC [dean of the faculty] believes the matter to be sufficiently serious that they cannot ignore it.”
Since the incident, G4S staff have examined ID from all visitors and recorded a log of who has gone in and out of the cells. The firm says this protocol has been put in place across Scotland.
A G4S spokesman said: “We are aware of the incidents and understand that an investigation is taking place into the circumstances. G4S reported the matter at the time to the relevant authorities and it is for them to decide what, if any, further action is to be taken.”
He added: “Security was previously over-familiar. If staff recognised the lawyer, they would not ask to see ID. It has been tightened up now so everyone has to produce ID.”
A spokesman for the Faculty of Advocates said: “This matter is currently before the Scottish Legal Complaints Commission and it would be inappropriate for the faculty to comment at this time.”
A Scottish Court Service spokesman added: “The security and management of the cell area at court is the responsibility of G4S as contracted to the SPS. SPS are aware of this incident and any review of security measures is a matter for them.”
Police Scotland and the Crown Office said they were unaware of any current cases involving the advocate.