Courts are frequently confronted with complaints about unequal treatment of various sorts, varying from legislative acts limiting the rights of inheritance of illegitimate children, to unequal taxation criteria for property taxes. The need to assess different cases of unequal treatment against the equality principle places before the courts a difficult task. The equality principle demands that the courts examine the reasonableness and justifiability of each specific case of unequal treatment, however different the subject. In doing so, the courts need to respect both the discretion or freedom of the party that is responsible for the difference in treatment, and the interests of the person or group that is disadvantaged by it. In order to enable the courts to take account of all interests at stake in any relevant equal treatment case, some variation in the intensity of review is indispensable. In some cases, it is appropriate to exercise restraint in assessing the justification for an inequality in treatment, while other cases call for the strictest scrutiny. In this contribution, the various factors that are relevant to the determination of the appropriate level of review are identified on the basis of a comparative study of the case law of the European Court of Justice, the European Court of Human Rights and the US Supreme Court. In addition, a standard is offered to balance intensity-determining factors pointing in different directions.