permissible if strictly necessary and sufficiently counter-balanced by adequate procedural guarantees to ensure an overall fair trial.134 Furthermore, states must exercise caution to ensure that the presumption of innocence is not jeopardized in the context of FTF offences. This requires that the burden of proof remains firmly on the prosecution to prove the guilt of the accused. The risk of inverting the burden of proof may arise, for example, if courts shift emphasis onto what the accused did not do to demonstrate opposition to terrorism.135 The risk may arise more directly in the context of laws that criminalize travel to certain areas unless the accused can prove a legitimate purpose.136 Gathering and Sharing Information and Evidence Within and Across Borders States face serious challenges in prosecuting FTFs and terrorist acts committed abroad due to the location of crimes, suspects and witnesses. In particular, it poses difficulties in accessing evidence, and there may be restrictions on the use of information received from foreign intelligence agencies. Therefore, states should dedicate serious attention to considering and sharing best practices on how to meet practical, evidentiary and jurisdictional challenges in a way that respects international human rights standards, including in relation to fair trial rights. UNSC Resolution 2396 (2017) places particular emphasis on gathering and sharing of information, intelligence and evidence, including from conflict zones, and on judicial measures and international co-operation to ensure that anyone who participates in the planning, preparation or perpetration of terrorist acts is brought to justice. In doing so, states should use all lawful means, consistent with human rights, to gather evidence of criminal conduct. Surveillance of individuals reasonably suspected of having committed FTF-related offences and the gathering, retention and sharing of information and personal data – including communication and digital data, and information about one’s movements – must not be done in a manner that erodes fundamental human rights protections. 134  Human Rights in Counter-Terrorism Investigations, OSCE/ODIHR, p. 48, op. cit., note 133; and Rowe and Davis v. The United Kingdom, ECtHR, Judgment of 16 February 2000. 135  An example of the difficult balance sometimes struck by courts in this context can be found in the case of Anjem Choudary and Mohammed Rahman in the United Kingdom. The two defendants were convicted in 2016 of inviting support for a terrorist organization by signing an oath of allegiance and broadcasting a series of lectures in which they claimed the “Islamic State” was a legitimate caliphate. The sentencing remarks noted that the defendants did nothing to condemn in the lectures any aspect of what the “Islamic State” was doing at the time and in that way indirectly encouraged violent terrorist activity. The judge accepted that there was no direct encouragement of any particular violent action and no evidence that anyone committed such acts as a result of the lectures, which constituted an important factor in limiting the sentences. See: R v Anjem Choudary and Mohammed Rahman, Central Criminal Court, Great Britain, Sentencing Remarks, 6 September 2016, International Crimes Database, <http://www.internationalcrimesdatabase.org/Case/3273>. 136  Australia’s Foreign Fighters Law of 2014 criminalized travel to a “declared area where terrorist organizations engage in hostile activity”, subject to the individual proving that presence there was for “a sole legitimate purpose”; see: “‘Foreign Terrorist Fighter’ Laws, Human Rights Rollbacks Under UN Security Council Resolution 2178”, Human Rights Watch, p. 14, op. cit., note 130. 42 Guidelines for Addressing the Threats and Challenges of “Foreign Terrorist Fighters”