The Scottish government legislation is intended to aid publication of a secret legal report on the Lockerbie bomber case.
The bill would let the Scottish Criminal Cases Review Commission decide whether to release the document on Abdelbaset al-Megrahi's appeal.
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.
Len Murray from the Justice for Megrahi group told the committee "the quickest and surest way" to have the report published would be to alter existing minor legislation rather than providing a new bill which "could create as many difficulties as it could solve".
Iain McKie, also from the group, agreed saying the legislation "as framed inhibits the release of information".
The concerns were echoed by Dr Jim Swire, whose daughter Flora was killed in the bombing of Pam Am flight 103 and who believes Megrahi is innocent.
Dr Swire went further suggesting the bill was "cumbersome and a delaying tactic" and there was an "orchestrated desire to delay the resolution of this dreadful case".
Robert Forrester also gave evidence on behalf of the campaign group.
The second part of the committee, where Ken Macdonald from the Information Commissioner's Office, Sir Gerald Gordon QC and James Chalmers from University of Edinburgh gave evidence, which can be viewed below:
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