It is clear what Jeremy Hunts defence will be.
Quite amazingly their is no requirement for any SPAD to act with impartiality on any quasi judicial decision before a minister. There are also no clear rules on ministerial behaviour on quasi judicial decisions in the Ministerial Code,
From the SPADS code of conduct
Special advisers are temporary civil servants appointed under Article 3 of the Civil Service Order in Council 1995. They are exempt from the general requirement that civil servants should be appointed on merit and behave with impartiality and objectivity so that they may retain the confidence of future governments of a different political complexion. They are otherwise required to conduct themselves in accordance with the Civil Service Code
They are exempt from all of the following clauses of the civil service code
9. You must:
provide information and advice, including advice to Ministers, on the basis of the evidence, and accurately present the options and facts;
take decisions on the merits of the case; and take due account of expert and professional advice.
10. You must not:
ignore inconvenient facts or relevant considerations when providing advice or making decisions; or
frustrate the implementation of policies once decisions are taken by declining to take, or abstaining from, action which flows from those decisions.
11. You must:
carry out your responsibilities in a way that is fair, just and equitable and reflects the Civil Service commitment to equality and diversity.
12. You must not:
act in a way that unjustifiably favours or discriminates against particular individuals or interests.
13. You must:
serve the Government, whatever its political persuasion, to the best of your ability in a way which maintains political impartiality and is in line with the requirements of this Code, no matter what your own political beliefs are;
act in a way which deserves and retains the confidence of Ministers, while at the same time ensuring that you will be able to establish the same relationship with those whom you may be required to serve in some future Government; and
comply with any restrictions that have been laid down on your political activities.
The only part of relevance is the section on honesty SPADS must not be influenced by improper pressures from others but there is no indication that a horses head was left in the SPADS bed.
Similarly the Ministerial Code says nothing about conduct of ministers and their aides regarding acting impartially on quasi judicial decisions before them. This is a convention but is not clearly set down in rules, indeed as lonng ago as 1949 an article referred to it as a term treated with distate by judges. The rules need to be urgently tightened.
The Ministerial Code says para 3.3
All special advisers must uphold their responsibility to the Government as a whole, not just their appointing Minister. The responsibility for the management and conduct of special advisers, including discipline, rests with the Minister who made the appointment. Individual Ministers will be accountable to the Prime Minister, Parliament and the public for their actions and decisions in respect of their special advisers. It is, of course, also open to the Prime Minister to terminate employment by withdrawing his consent to an individual appointment.
And in the principle of public life section
In carrying out public business, including making public appointments, awarding contracts, or recommending individuals for rewards and benefits, holders of public office should make choices on merit