The decisions of this Court further establish (a) that a law may be constitutional even though it relates to a single individual if, on account of some special circumstances or reasons applicable to him and not applicable to others, that single individual may be treated as a class by himself; (b) that there is always a presumption in favour of the constitutionality of an enactment and the burden is upon him who attacks it to show that there has been a clear transgression of the constitutional principles; (c) that it must be presumed that the legislature understands and correctly appreciates the need of its own people, that its laws are directed to problems made manifest by experience and that its discriminations are based on adequate grounds; (d) that the legislature is free to recognise degrees of harm and may confine its restrictions to those cases where the need is deemed to be the clearest ; (e) that in order to sustain the presumption of constitutionality the court may take into consideration matters of common knowledge, matters of common report, the history of the times and may assume every state of facts which can be conceived existing at the time of legislation; and (f)that while good faith and knowledge of the existing conditions on the part of a legislature are to be presumed, if there is nothing on the face of the 38 298 law or the surrounding circumstances brought to the notice of the court on which the classification may reasonably be regarded as based, the presumption of constitutionality cannot be carried to the extent of always holding that there must be some undisclosed and unknown reasons for subjecting certain individuals or corporations to hostile or discriminating legislation.