The situation of every person who calls us or walks through our door is unique. Every case is different, and a book could be written on the amount of factors that go into evaluating whether someone has a case. Almost every case we look at, however, must contain at least three main elements to justify moving forward. The first one is liability.
Is someone (legally) at fault for what happened?
The first question we have to answer is whether someone is legally to blame for what occurred. If the potential wrongdoer is a member of the general public, the question is whether that person acted reasonably under the circumstances. If the potential wrongdoer is a member of a profession, the question of reasonability is answered by asking whether the person fell within or below the acceptable standard of care in their profession and industry (this often requires an expert in that field to provide opinions regarding what the standard of care in the industry is).
If everyone under the circumstances acted reasonably, a person does not have a case simply because they were injured--an accident does not always amount to liability and negligence. Additionally, all professions and industries have a range of errors that are considered within the standard of care due to the common risks associated with that profession or industry. For example, depending on the operation involved there are mistakes the surgeon is allowed to make and avoid legal action due to the common risks associated with that kind of surgery. Police officers are given wide latitude regarding the errors they are allowed to commit due to the kinds of split-second judgement calls they have to make in the field on a daily basis.
In other words, stuff happens. People make mistakes every day that are acceptable. To have a case, the wrongdoer's actions have to be considered unreasonable and unacceptable by society and law.
There are other things that can affect liability that must be considered. Generally, breaking the law is considered unreasonable as a matter of law. Some laws specifically define whether certain actions taken by certain citizens or professionals are negligent (or not), or require a standard higher than reasonability to prove wrongdoing. Some laws protect certain people from suit all together, or substantially limit the kind of legal action that can be taken against them.
We also have to consider the actions of the injured person. If the injured person also did things that were unreasonable under the circumstances that led to injury, we have to evaluate how much each party is to blame for what happened (As I will discuss in Part II, any damages that are awarded to an injured party will be offset by their own percentage of wrongdoing). If the injured person agreed to assume particular risks of an activity or signed a document waiving another party from responsibility, this can often--but not always--eliminate liability even in situations where, without the waiver, the wrongdoing would be considered unreasonable.