Government legislation to aid publication of a secret legal report on the Lockerbie bomber case may fail to work properly, it has been claimed.
The bill would let the Scottish Criminal Cases Review Commission decide whether to release the document on Abdelbaset al-Megrahi's appeal.
Senior QC Sir Gerald Gordon said publication could still be hampered by data protection laws.
Lockerbie campaigner Dr Jim Swire expressed a similar concern.
The Scottish government is holding talks with UK ministers to help ensure data protection issues can be overcome.
Megrahi, the only person to have been convicted in connection with the 1988 attack, which killed 270 people, returned home to Libya in 2009.
He dropped the appeal against his conviction in order to secure his early release. Meghrahi, who was diagnosed with terminal cancer, returned to Libya after being released from jail in Greenock on compassionate grounds.
A report on the case sent to the appeal court by the Scottish Criminal Cases Review Commission (SCCRC), which investigates possible miscarriages of justice, has not been released.
The Scottish government's Criminal Cases Bill suggests several legal reforms, including giving the SCCRC new powers to publish reports in appeal cases it has looked into, where such appeals have been abandoned.
Sir Gerald - who was member of the SCCRC board at the time Megrahi's application was considered and has seen the commission' s report - said the decision on publishing the report should rest with politicians.
"I do not think that determining whether publication of the Statement of Referral (SOR) is appropriate, far less deciding to publish it, is itself an appropriate function for the SCCRC," said the former sheriff and high court judge, in a submission to Holyrood's justice committee.
"The SCCRC was set up to decide whether a case should be referred to the high court - the decision whether or not to publish the SOR is a political one and should be decided by politicians."
Sir Gerald added that, while he had no expertise in the field of data protection: "It is clear that the parliament has no power to dispense with the Data Protection Act, and there may even be a question as to whether it can make any specific provisions regarding the disclosure of personal data.
"If that is so, there would seem to be little point in legislating on the matter unless and until Westminster does what is necessary."
The concerns were echoed by Dr Swire, whose daughter Flora was killed in the bombing of Pam Am flight 103 and who believes Megrahi is innocent.
In a submission to the committee, the Justice for Megrahi campaign, of which he is a member, said existing legislation could be used to block publication.
"Under the bill, common law and statutory obligations of secrecy or confidentiality could be founded upon by the suppliers of the information, or any persons directly affected by it, in any legal action taken by them to block disclosure," it stated.
The group argued that secondary legislation could be introduced to overcome such a hurdle.
Ken Macdonald, from the office of the UK information commissioner, which deals with data protection issues, said the Scottish government bill would help ensure publication of the report "meets with the provisions" of the Data Protection Act.
He added: "The bill contains a robust legislative framework which will ensure that such disclosure is fair and lawful."
A Scottish government spokesman said: "The bill puts in place a framework that will enable, as far as possible within devolved competence, the disclosure of information by the SCCRC in cases where an appeal has been abandoned or has fallen.
"This government continues to do all we can to achieve publication of the statement of reasons in the Al-Megrahi case, while of course we cannot legislate on reserved matters."