As far as the first scenario is concerned Natalia decided to frighten Otto and Pamela. In order to prove criminal liabilities we need to prove Actus reus , Mens rea and Causation. In the given scenario we see that due to angriness Natalia wanted to frighten her former boyfriend and his new girlfriend, Pamela. To fulfil her intention she took some petrol and poured it through the letterbox of the house where the couple were living, setting fire to it by using a lighted match. So there is Actus reus and Mens rea existed. Unknown to Natalai Otto and Pamela were absent at the moment and Ruth, Pamela’s mother, was staying at the house to care for Pamela’s children, Steven and Tina. As a result Ruth died at the scene and Pamelas children Steven and Tina badly injured. It is clearly stated in the scenario that it was unknown to Natalia. And her intention is to frighten Otto and Pamela. So it may be said that guilty mind i.e. Mens rea to frighten Ruth Steven and Tina is absent there. In the given scenario it is expressly stated that Ruth died on the spot due to fire caused by guilty act done by Natalia. So there is Causation and no dought that the death of Ruth is the result of Natalias act. If that is the case Natalia may be held criminally liable for the death of Ruth. There also a pre arranged plan and state of mind existed.
In the given scenario it is expressly stated that Natalias intention was to frighten Otto and Pamela. Not to frighten Ruth, Steven and Tina. But it can be infrared that it was not unknown to Natalia to live Steven and Tina with their mother Pamela together with Otto in that house. Criminal intention can be further broken into two groups, direct and oblique. A direct intention is the willful desire to commit an act. It must be understood that the intention sufficient to amount to mens rea is only the intention to perform the required criminal act, not an intention for the result to occur. Assault occasioning actual bodily harm is a good example here. The requisite mens rea is intention to cause frighten. If Natalia intentionally frighten Ruth and harm results, She is guilty of the offence. The fact that she does not intend harm is irrelevant. She intended to do the act, and harm is simply a by-product. Mens Rea does not have to be proven in relation to one or more elements comprising the actus reus although intention, recklessness or knowledge may be required in relation to other elements of the offence. Natalia should have waited until Otto and Pamela was seen to live in the house before starting the fire. The reasonable person would have foreseen a probability that people would be exposed to the risk of injury. Anyone in the house, neighbors, people passing by, and members of the fire service would all be in danger. In English law provides a statutory framework within which mens rea is assessed. It states: English law is a formal term of art that describes the law for the time being in force in England and Wales. ... A court or jury, in determining whether a person has committed an offence, (a) shall not be bound in law to infer that he intended or foresaw a result of his actions by reasons only of its being a natural and probable consequence of those actions; but (b) shall decide whether he did intend or foresee that result by reference to all the evidence, drawing such inferences from the evidence as appear proper in the circumstances. Therefore, the jury is allowed wide latitude in applying a hybrid test to impute intention or foresight (for the purposes of recklessness) on the basis of all the evidence. If the prosecution can prove Actus reus, Mens rea and Causation Natalia may be held liable. Now we can discuss whether any self-defence for Ntalia from criminal liabilities. In order to release from criminal liability Natalia has to prove that, Otto and Pamela provoked her, she has no intention to frighten Ruth, Steven and Tina. And the death of Ruth Steven and Tina was not her intention as well. We need to discuss whether any sudden provocation existed which may support her from the Criminal liabilities. In the given scenario we see that Natalia had an affairs with Otto. Which make Natalia incensed and she was provoked. Though there is no clear information in the scenario that there is any act or omission done by Otto that may have resulted any sudden provocation. Provocation may be a valid defence. In this scenario we see that Natalia planed for frightening Otto and Pamela. She had reasonable time to review her plan. Moreover she arranged everything after taking the decision of frighten. So it can be assumed that there was no such sudden provocation present in the scenario. Though Natalia may not have desired Ruth,s death Similarly, he may never consciously have considered the damage, but the murder may under the Criminal Damage Act 1971 will be intended. This is distinguishing between the direct intention, which is the main aim of the plan, and the oblique intention, which covers all the intermediate steps. More generally, a person directly intends a consequence when his purpose or aim is to cause it even though he believes that the likelihood of it succeeding is remote. In R v Mohan it was held that direct intention means, "aim or purpose" - "a decision to bring about, insofar as it lies within the accused's power, the commission of the offence. No matter whether the accused desired that consequence of his act or not." Sometimes, by accident, a plan miscarries and the accused achieves one or more unintended consequences. In this situation, the accused is taken to have intended all of the additional consequences that flow naturally from the original plan. This is tested as matters of causation and concurrence. "A man must be considered to be responsible for the probable consequences of his act. To demand more of him is too harsh a rule, to demand less is to ignore that civilised order requires the observance of a minimum standard of behaviour."
Liabilities of Natalia in regards to death of Steven and Tina: As far as Tina and Stevens death is concerned Natalias Actus reus was not direct cause of their death. In the given scenario it is expressly stated that the doctors gave Steven a sedative to which he had a strong reaction and died. And about Tina the anaesthetist failed to notice that the oxygen supply tube had become disconnected and Tina died. So death of Steven and Tina was not the direct effect of Natalias actus reas. There is a remote relation between the cause of their death and Natalias guilty act. However still there is question whether it is too remote or not? The essential element i.e. causation needs to be proved. In the given scenario it is seen that Steven and Tina were taken to hospital suffering from serious burns. So it is clear that they were injured caused by fire. So liabilities may for such injury be imposed on Natalia. In regards of their death she may not be absolutely liable but she may not free from criminal liabilities of their death.
Liabilities of Doctors and Anaesthetist in regards to death of Steven and Tina:
As far as the second scenario is concerned it is expressly stated that the doctors gave Steven a sedative to which he had a strong reaction and died. And about Tina the anesthetist failed to notice that the oxygen supply tube had become disconnected and Tina died. Prima-facie that the both have failed to take reasonable cares. In order to establish Medical Negligence of the Doctor and anesthetist it needs to be proved that they have duty to care, they britches of that duty, and what would do a reasonable person on that matter. Generally medical negligence differs from other litigations because claimant must rely on expert medical evidence. In the given scenario it is expressly stated that the anesthetist failed to notice that the oxygen supply tube had become disconnected. As a result Tina had died. It is the duty of an anesthetist to check the oxygen supply before using anesthesia. So there is a clear evidence of breach of duty. In that particular case if we apply a reasonable person test anesthetist may be held liable for negligence. In regards to Steven death the doctor may have passed the reasonable person test because it may not possible to identify the reaction of sedative especially for a seriously burnt patient. Negligence may not be proved in that case. If that is the case, Doctor may not be liable for any criminal act except otherwise. In a negligence suit, the plaintiff has the burden of proving that the defendant did not act as a reasonable person would have acted under the circumstances. The law recognizes that even a reasonable person can make errors in judgment in emergency situations. Therefore, a person's conduct in an emergency is evaluated in light of whether it was a reasonable response under the circumstances, even though, in hindsight, another course of action might have avoided the injury. In some circumstances failure to anticipate an emergency may constitute negligence. If the prosecution proves that there is a negligence liabilities may have been arisen. Liabilities of Vince death:
In the given scenario it is expressly stated that Vince was a neighbour and Ruth, Steven and Tina were rescued by him, as a result Vince suffered from breathing difficulties caused by smoke inhalation. Later he died from a previously undiagnosed heart abnormality. From this scenario it can be said that he took the risk not by force or pressure of any third party even though it was not his duty to rescue them. Moreover there is no evidence of Medical negligence found in the given scenario. So we may assume that cause of Vince death occurred from his own risk. So there may not have any criminal liabilities arisen.
1) Criminal Justice Act 1967
2) Professional Negligence in English Law
3) The law of Tort
 Section 47 of the Offences Against The Person Act 1861
 S8 Criminal Justice Act 1967
 Under s8 (b)
 (1975) 2 All ER 193
 Viscount Simonds held at pp422-423: