There is one simple answer to US Senators wanting UK and Scottish Ministers to attend Senate hearings to answer for their conduct: “Never”.
UK Ministers are answerable to the UK Parliament. If the US needs clarification of UK policy or actions it should seek it through diplomatic channels. I did not agree with the Scottish decision, but they had every right to make it following their process of law.
The UK Parliament does not demand that the US administration comes to answer here when US citizens or companies behave in ways we dislike.
The last government signed a lop sided extradition treaty with the USA and gave to the EU the extraordinary power of the European arrest warrant.
It is high time the UK defended and reasserted its own judicial and decision making integrity. The US may wish to assert all types of extraterritorial jurisdiciton, but that is no reason for us to give in or to take it seriously.
It is also time the US gave up its vendetta against BP. They should instead have a full enquiry into what went wrong in the Gulf, examining objectively the mistakes made by all the companies concerned with the well, and the actions and inactions of the US safety and oil regulators.