Leading article: UK officials must come clean about rendition

Even welcome regime change can have treacherous effects, transforming once-needed allies into enemies, or vice versa. And rarely have the risks been more graphically illustrated recently than with Libya, where a former dissident, Abdelhakim Belhaj, is now head of post-Gaddafi Libya's armed forces. Not only is he suing the British government for allegedly colluding with Colonel Gaddafi to have him forcibly returned to Libya and tortured, but – as of yesterday – he is also taking legal action against a named official: Jack Straw, Foreign Secretary in the last British government.

The drama has unfolded in two stages. The first was last September, when documents found in Tripoli appeared to support claims that British intelligence had supplied information that allowed the CIA to spirit the fugitive Mr Belhaj and his wife back to Libya in 2004. The second has played out over the past week, after a newspaper quoted sources alleging that Mr Straw personally signed off on the operation. The former cabinet minister is accused of complicity in torture and misfeasance in public office.

It is thought to be the first time that such proceedings have been launched against a former Foreign Secretary – which is one reason why the full implications are as yet unclear. That there are implications, however, and potentially serious ones – both positive and negative – is beyond doubt. On the plus side, the latest lawsuit could mean that real light is finally cast on the still-murky subject of rendition and the involvement of the last British government. That rendition – the clandestine detention and transfer of suspects to their own country or third countries – and interrogation under torture were weapons deployed by the United States during George Bush's "war on terror" is known and largely admitted. What is less known and mostly not admitted – though not expressly denied either – is how much the British government of the day knew about, and actively co-operated with, such actions with its transatlantic ally.

Co-operation may have taken many forms: from supplying information that permitted rendition (as Mr Belhaj's lawsuit alleges), through facilitating it by, for instance, allowing the use of planes or refuelling stops, to providing the questions and witnessing, or even conducting, interrogations that entailed torture. Such accusations have featured in the testimony of many former British prisoners at Guantanamo, and in most cases the government has paid compensation rather than have the charges aired in court. The justification given is that crucial intelligence methods might be divulged. The suspicion must be, however, that there is another consideration: fear that the real role of the British state in the ill-conceived "war on terror" would be laid bare. If the lawsuits initiated by Mr Belhaj force genuine information about this shameful chapter into the open, that can only be a good thing. The people of this country have a right to know what was being done in their name.

The novelty of Mr Belhaj's latest lawsuit, however, is that it names Jack Straw personally. And here the arguments become more complicated. Of course, individual ministers – like military commanders – must act within the law, hence the controversy about Lord Goldsmith's rulings on the Iraq war. But does knowledge of rendition or torture break the law? Or would it take active involvement? What about ordering information to be passed to the US (a major ally)? And does the legal responsibility reside with the minister or the Prime Minister or the government collectively?

In principle, a minister's responsibility is political – to Parliament – rather than judicial. But are there instances where that line is crossed? It might be salutary for that question to be tested. But if ministers are to be held personally accountable before the courts for their (or their boss's) decisions, the risk is that no significant decisions – right or wrong – will be taken at all.