- 29 A B - displacement of the well-established common law principles for injunctions in aid of the criminal law. Such a drastic step is unwarranted A B when those principles can be suitably developed to give effect to the C mandates in the NSL for safeguarding national security. D D Third, necessity of the injunction is a context-specific 50. E F question, entailing a careful evaluation of all the relevant circumstances. Since circumstances vary, the categories of cases where the injunction may be granted are not closed. G C E F Based on the authorities discussed above, it can be readily inferred that the injunction is necessary: H G H (1) I where the past or threatened conduct of the defendants, such as wide-spread, persistent flouting of the criminal law, clearly shows that enforcement by prosecutions alone will not J I J achieve the public interest purpose of safeguarding national K security; or L (2) where there are situations in which it is imperative for the court to intervene at once to prevent the continuation of an M unlawful state of affairs or conduct which might give rise to N K L M N imminent threats to national security; or result in further, serious or even irreparable damage to national security. O P P 51. We turn next to the question of deference. Q R O Q 52. The concept of judicial deference to the executive’s R evaluative assessment on national security is well-established at common S T law. For more recent authorities, see CCSU v Minister for Civil Service [1985] AC 374; Secretary of State for the Home Department v Rehman S T [2003] 1 AC 153; R (Begum) v SIAC [2021] AC 765. It is based on both U U V V