The incidents were recorded by HM Inspectorate of Prisons for Scotland (HMIPS) during a review of custodial operations at Edinburgh Sheriff Court.
The watchdog's report describes it as “unacceptable” for people to be transferred from the escort vans dressed in such a way and ordered Police Scotland to ensure they have appropriate clothing.
It says: “When observing prisoners being removed from escort vans it was noted that one female prisoner arrived in her nightclothes, two prisoners were in shorts, one prisoner appeared to be in his underwear and one prisoner had no footwear.
“Police Scotland should ensure that those arriving from police custody are appropriately dressed for the journey and their subsequent court appearance.
“It is unacceptable that individuals are expected to appear in a court of law in their underwear or nightclothes.”
HMIPS made the findings during an inspection of court custody provision in June.
Inspectors found the court's custody unit to be well-run with motivated staff who worked as a team.
The report, published on Wednesday, also says clarification over the provision of medical information was urgently needed to ensure custody staff can safely manage prisoners.
Chief Superintendent Garry McEwan, head of the criminal justice services division, said: “We note the report published by HMIPS today and are keen to work with our partners on the recommendations.
“Police Scotland ensure that all those in police custody are treated with dignity and respect.
“Alternative footwear and clothing is stocked in all primary suites and where practical is offered.
“All relevant health information is recorded as part of the personal escort record which remains with the prisoner when they are transferred in to the custody of G4S.”
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