In the 19 years since Pan Am 103 was blown up over Lockerbie, killing 270 people, Scottish justice and international diplomacy have been problematically knotted. The relationship between the Scottish and the UK Governments is proving a particularly tangled strand. International relations have moved on since both the atrocity and the 2001 trial under Scots law at Camp Zeist, which convicted Abdelbaset Ali Mohmed al Megrahi and required him to serve his sentence in Scotland. In particular, the so-called "deal in the desert" between Tony Blair and Colonel Gaddafi last year led to an agreement on the repatriation of Libyans in British jails, opening the possibility of Megrahi being transferred to Libya. Alex Salmond and Kenny MacAskill, the Scottish Justice Secretary, want Megrahi, the highest-profile Libyan prisoner here, to be excluded from the prisoner transfer agreement.

The insistence by UK Justice Secretary Jack Straw, in a letter yesterday in The Herald, that the agreement provides a framework for transfer, but not a deal for any specific prisoner, and that, in the case of Megrahi, the decision is "a matter for Scottish ministers, not the UK Government", intended to provide reassurance, has ignited an attack from Alex Salmond. That is because it ignores the possibility of a decision by ministers being overturned by a judicial review, something Mr Straw had conceded in a letter to the Scottish Government.

On one aspect Mr Straw is in agreement with the Scottish Government and the Crown Office: Megrahi cannot be considered for transfer until outstanding legal proceedings in Scotland have been completed. That is pertinent because he is appealing against his conviction, a process complicated by a dispute over whether the prosecution will reveal documents from a foreign source. That remains to be dealt with by the courts and, if Megrahi wins his appeal, the prisoner transfer problem will disappear. The question at the heart of it, however, will not have been resolved.

This case is too important, not least to the relatives of those killed in this act of terrorism, for the principles of justice to be lost in the heat of political point-scoring when they should be embedded in transparency. The misunderstandings began with the Libyans believing prisoner transfer would include Megrahi, and the Scottish Government was kept in the dark about the deal in the desert. Mr Straw is right to see Tripoli's renunciation of terrorism and dismantling of its WMD programmes as significant steps, but the recent signing of a £450m oil exploration contract for BP leaves an unfortunate suspicion that commercial concerns have been uppermost in the new relationship between the UK and Libya. The memorandum of understanding agreed last May should be a means of helping to re-integrate Libya with the international community, but it must be a secondary consideration. Justice is paramount.