Under s. 78 of the Police and Criminal Evidence Act 1984, the trial judge may exclude evidence if it would have an adverse effect on the fairness of the proceedings if it were admitted. Breach of Code D does "not" automatically mean that the evidence will be excluded, but the judge should consider whether a breach has occurred and what the effect of the breach was on the defendant. If a judge decides to admit evidence where there has been a breach, he should give reasons, and in a jury trial, the jury should normally be told "that an identification procedure enables suspects to put the reliability of an eye-witness’s identification to the test, that the suspect has lost the benefit of that safeguard, and that they should take account of that fact in their assessment of the whole case, giving it such weight as they think fit". Informal identifications made through social media such as Facebook (often in breach of Code D), pose particular problems for the criminal courts.