66 238. In the 1999 Report on the Situation of Human Rights in Colombia, for example, the Commission addressed the use of anonymous witnesses and explained that: The defendant is also prevented from carrying out any effective examination of the witnesses against him. The right to examination is largely important, because it provides the defendant with the opportunity to question the witness’s credibility and knowledge of the facts. The defendant cannot adequately examine a witness if he does not possess any information regarding the witness’s background or motivations and does not know how the witness obtained information about the facts in question. The "faceless" justice system thus also leads to the violation of Article 230 8(2)(f) of the American Convention, guaranteeing the right of the defense to examine witnesses. 239. Other international human rights bodies have denounced the use of anonymous witnesses as antithetical to the right of defense that underlies all due process. Thus, the Human Rights Committee held that a justice system that allows the use of anonymous witnesses does not comply with Article 14 of the International 231 Covenant on Civil and Political Rights. 240. Nevertheless, there are circumstances in which the investigation and prosecution of certain types of crime, including crimes of terrorism, can expose those who cooperate with the administration of justice to serious threats against their lives and physical integrity. Clearly, States also have the obligation to prevent violence against 232 those who cooperate with the administration of justice, and to protect their rights to life and physical integrity. In such cases, international case law has accepted that certain exceptional measures can be taken to protect witnesses from the real dangers that their cooperation in criminal cases may expose them to, provided those exceptional measures do not infringe upon the essential guarantees of due process, a matter that must be determined on a case-by-case basis. As the Commission wrote, “this may in turn require that certain exceptional measures be taken to protect the life, physical integrity and independence of judges on a case by case basis, always providing, however, that the nature or implementation of such measures does not compromise a defendant’s non-derogable fair trial guarantees, including the right to a defense and the right to be tried by a competent, 233 independent and impartial tribunal.” And as the Commission elaborated in its Report on Terrorism and Human Rights, The right of a defendant to examine or have examined witnesses presented against him or her could also be, in principle, the subject of restrictions in some limited instances. It must be recognized in this respect that efforts to investigate and prosecute crimes, including those relating to terrorism, may in certain instances render witnesses vulnerable to threats to their lives or integrity and thereby raise difficult issues concerning the extent to which those witnesses can be safely identified during the criminal process. [See IACHR, Report Colombia (1999), Chapter V, paragraphs 67-69]. (…) Subject to these caveats, procedures might in principle be devised whereby witnesses’ anonymity may be protected without compromising a defendant’s fair trial rights. Factors to be taken into account in evaluating the permissibility of such procedures include the sufficiency of the grounds for maintaining a particular witness’s anonymity and the extent to which the defense is nevertheless able to challenge the evidence of the witness(es) and attempt to cast doubt of the reliability of their statements, for example through questioning by defense counsel. Other pertinent considerations include whether the court itself is apprised of the witness’s identity and is able to evaluate the reliability of the witness’s evidence, and the significance of the evidence in the case against the defendant, in particular whether a conviction may be based solely or to a decisive extent on that evidence. [See, for example, European Court of Human Rights, Doorson v. the Netherlands, March 26, 1996, R.J.D. 1996-11, No. 6, paragraphs 70-76. (…) The Statutes and the Rules of Procedure of the International Criminal Tribunals for the Former Yugoslavia and for Rwanda constitute examples of contemporary efforts to fairly adjudicate serious crimes in circumstances where participants may be particularly vulnerable to threats, and include 230 IACHR, Third Report on the situation of human rights in Colombia, OEA/Ser.L/V/II.102 Doc. 9 rev. 1, February 26, 1999, Chapter V, paragraph 123. 231 UN, Human Rights Committee – Consideration of reports submitted by states parties under Article 40 of the Covenant – Concluding observations by the Human Rights Committee – Colombia. UN CCPR/C/79/Add.76, April 9, 1997, paragraph 21. 232 American Convention on Human Rights, Article 1(1); IACHR, Third on the situation of human rights in Colombia, OEA/Ser.L/V/II.102 Doc. 9 rev. 1, February 26, 1999, Chapter V, paragraphs 67-70. 233 IACHR, Report on Terrorism and Human Rights, OEA/SER.L/V/II.116, Doc. 5 rev. 1, corr., October 22, 2002, paragraph 233.