New legislation could be passed to direct Gardaí to appear before the Kingsmill inquest into an IRA massacre, a lawyer has said.
A coroner in Northern Ireland is seeking intelligence and other information held by the Garda about the sectarian shooting dead of 10 Protestant workmen by republicans in south Armagh in 1976.
Garda Commissioner Noirin O'Sullivan cannot direct an officer to give evidence to the inquest, which is due to resume next month, without new legislation.
Sean Doran QC said: "The attendance of a garda at legal proceedings outside the jurisdiction would have to be done properly under the auspices of a direction by the Commissioner but the legal authority to give such a direction is absent and that is the reason why legislation is being considered to deal with this particular issue."
Coroner Judge Brian Sherrard said there appeared to be a blockage to a garda witness attending voluntarily.
Legal counsel for relatives of the dead said the attack began with the hijacking of a vehicle and the escape of the gunmen into the Republic of Ireland and it was only humane that a garda should appear to guide the inquest through the documents.
The textile workers were travelling home from work when their minibus was ambushed.
They were asked their religion then lined up on a country road and shot dead in a sectarian attack blamed on the IRA. Alan Black survived despite being shot 18 times.
Relatives of those killed want details from the Gardaí about weapons used, intelligence and the getaway van employed by the gunmen.
They have accused authorities here of only paying "lip service" to their concerns.
The coroner is seeking material held in the Republic of Ireland relating to Kingsmill and is to make a formal request within days.
He is considering calling a witness from the Gardaí to help make sense of any documents he receives and shed some light on the force's methodology during the period in question.
He acknowledged the force's willingness to help and said he did not fully understand the reason why the legal framework precluded a garda appearing on a voluntary basis.
Alan Kane QC, for some of the families, said: "After all these years, the least that these relatives can expect is ordinary decency and humane cooperation by volunteering a witness."
He accused the authorities in the Republic of Ireland of creating a road block to scrutiny of any action.
"There are many elderly people anxious to bring these matters to conclusion.
"If the documents are offered, it is little to expect that the Gardaí would not volunteer someone who would come to explain procedures in place at the time, investigative methods, intelligence practices, subject to the protection you (the coroner) would afford to them."
Mr Doran met with the legal authorities in the Republic of Ireland about the case recently.
He said the legal advice to the Gardaí was that the directing of its members to provide sworn testimony to a Northern Ireland inquest does not come into the provisions of EU law on mutual assistance or within domestic law.
He added the consideration of new legislation to allow that to happen could take some time.
He said: "Meanwhile, the offer remains to make available a senior officer of An Garda Siochana who is familiar with the case to meet the coroner and his representatives to assist in any case within the legal framework."