Use of lethal force:
Back in 1995, in McCann and others v UK (1996) 21 EHRR 97, the E Ct HR found by a 10 to 9 majority that the UK was in breach of Article 2 when British soldiers killed suspected IRA terrorists in Gibraltar. This was a highly controversial decision but the European Court of Human Rights (E Ct HR) set out the general principles applicable to the use of lethal force by the military, police and security forces. At the time,
English law said little about this beyond permitting the use of 'reasonable force' in the prevention of crime etc - Criminal Law Act 1967 s.3. The McCann case established that the State is expected to exercise due diligence and care even in anti-terrorist operations and the ECtHR felt that, because of Article 2, it had a duty to examine most carefully whether the authorities of a State had fulfilled that duty when they kill somebody.
Those principles have been applied and developed in later cases. In some circumstances, there is a positive obligation on States to protect life - often referred to as the 'Osman Duty' from the case of Osman v UK (2000) 29 EHRR 245 actually decided by the E Ct HR in 1998. This duty was recognised by the House of Lords in Re Officer L  UKHL 36 and Chief Constable of Hertfordshire Police v Van Colle  UKHL 50.
Re Officer L was a case from Northern Ireland concerning whether Police and Security Force witnesses could give their evidence anonymously to an Inquiry. The issue in the Van Colle was - if the police are alerted to a threat that D may kill or inflict violence on V, and the police take no action to prevent that occurrence, and D does kill or inflict violence on V, may V or his relatives obtain civil redress against the police, and if so, how and in what circumstances?
Coroners and Inquests:
A further development is the need for a full and effective investigation into deaths occurring when state agencies are involved - R (Middleton) v HM Coroner for Somerset  1 AC 182 where the House of Lords held that, in order to be compliant with Article 2, the Coroners Act 1988 s11 had to be interpreted so that 'how' the deceased came by death meant not only 'by what means' but also 'in what circumstances.' An effective investigation ensures that, as far as possible, the full facts are brought to light; that culpable and discreditable conduct is exposed and brought to public notice; that suspicion of deliberate wrongdoing is allayed ; that dangerous practices are rectified; and that those who have lost a relative may at least have the satisfaction of knowing that lessons learned from the death may save the lives of others - speech of Lord Bingham in R (Amin) v Secretary of State for the Home Department  UKHL 51 at para. 31. See also Hillsborough - Fresh Inquests - the question of Article 2 compliance and the post of 12th December 2012 on the murder, in 1989, of Pat Finucane.
Article 2 came into play in the case of Dianne Pretty v UK (2002) 35 EHRR 1. The Director of Public Prosecutions (DPP) had refused to give an undertaking that Mrs Pretty's husband would not be prosecuted under the Suicide Act 1961 should he assist her to commit suicide in the event that her motor neurone disease became unbearable. The ECtHR held that the right to life did not imply its opposite - a right to die. States are not under any obligation to permit voluntary euthanasia.
In 2009, the House of Lords decided - R (Purdy) v DPP  UKHL 45 . Their Lordships directed the DPP to draw up a policy relating to prosecutions under the Suicide Act 1961 s2(1) and this was duly done (here). This is an example where the strict law has not been changed but the application of the law has been modified.
Duty of hospital to parents of mentally ill patient:
A further important case was Supreme Court of the U.K. - Rabone v Pennine Care NHS Foundation Trust  UKSC 2 - and blogpost 8th February 2012. In this case, the Supreme Court of the UK held that obligations under Article 2 were owed to a mentally ill patient who was not detained under mental health legislation and who attended hospital voluntarily for help / treatment. The hospital was held to be in breach of those obligations and the girl's parents were held to be 'victims' of that breach.
In these times, there is a great deal of anti Human Right rhetoric. In this context, it is worth noting the following from Lady Hale's judgment:
"A hospital trust, in breach of its duty of care towards its patient, allowed a young woman, who was suffering from a severe depressive episode with psychotic symptoms and had been admitted a week earlier after a serious suicide attempt, to go home on leave for two days. The only support plan was the care of her parents who were not in favour of her being allowed home. The following day she hanged herself from a tree in a well-known local beauty spot, at last succeeding in the suicide which she had previously attempted and seriously threatened even more often. The hospital trust has admitted liability to her and paid a sum in compensation to her estate. So why, some might ask, are we here?
We are here because the ordinary law of tort does not recognise or compensate the anguish suffered by parents who are deprived of the life of their adult child. In this day and age we all expect our children to outlive us. Losing a child prematurely is agony. No-one who reads the hospital’s notes of the series of telephone calls made by this patient’s father to the hospital on the night in question can be in any doubt of that; or that the agony may be made worse by knowing that the loss both could and should have been prevented. It is not surprising, therefore, that parents are among the recognised victims when the right to life of their child, protected under article 2 of the European Convention for the Protection of Human Rights and Fundamental Freedoms, is violated. It is also not surprising that, ... , they are victims, not only of the state’s failure properly to investigate the death, but also of the failure effectively to protect their child’s life." [My emphasis].
It will be noted that the original Article 2 permitted the death penalty. Whilst that was the original position, the death penalty is no longer permissible in any circumstances. This change came about with Protocol 6 which prohibited the death penalty except in time of war and Protocol 13 which now prohibits it under all circumstances.