matter is Osman v UK which overruled the UK court's decision in Hill v West Yorkshire as to the fact that public bodies could not be held to be negligent. Some cases establish further obligations for states. For instance, LCB v UK establishes a positive obligation for states to take "appropriate steps to safeguard the lives of those within their jurisdiction." Makaratzis v Greece pushes these obligations further, so that the state must have mechanisms to deter offenses against people. This was initially applied to the use of firearms. Although the court recognized the defensive benefits in gun ownership, it found a much larger threat in unchecked gun use. Duty to investigate suspicious deaths The investigation must be effective, independent and prompt. The duty to investigate is even stronger where the death has occurred whilst a person was detained by the state. The leading authority on this is Salman v Turkey (2000). Use of force and exceptions in paragraph 2 This constitutes the negative obligation of the state under the convention. The states must under article 3 refrain from any random deprivation of life. This article however offers states a few exceptions to that rule. This constitutes a license to use force and is not to be construed as a license to kill. The exceptions are well defined and are subject to a very narrow interpretation by the Court. There are three conditions set by the court: The use of force must be absolutely necessary; It must be in defence of a third party; It must be subject to a proper and effective investigation which is both impartial and independent. Key rulings in this matter are McCann and Others v United Kingdom, Makaratzis v Greece, and Nachova and others v Bulgaria. Beginning of life In 1980, the Court ruled out the foetal right to sue the mother carrying the foetus. In Paton v. United Kingdom, it was decided that the life of the foetus is "intimately connected with, and cannot be regarded in isolation from, the life of the pregnant woman". The key ruling was Vo v France where the court ruled that due to lack of consensus over the matter in the member states, the court allows a margin of appreciation (usually reserved only for the derogable rights) to each state to determine whether a foetus falls under the protection of article 2. The court, as it usually does