The law is generally not an absolute. It is often a matter of interpretation. The law is determined by looking first, at the words written by a legislature or at regulations issued by an administrative agency, and second, interpreting those words. Facts too are generally not an absolute. They are often a matter of interpretation.
Different people see the same things in different ways.
Since the resolution of a legal case is determined by applying the law and the facts, the facts must be thoroughly investigated. A lawyer must not only know your understanding of the facts, but also must know your opponent's version of the facts. Most important to remember is that arguments are based on the actual facts of a given situation. Thus no lawyer can or should give you an opinion without knowing both the law and the facts. The first decision the consumer must make is whether to get a lawyer.