Why Do We Need The Law
“I have gained this from philosophy: that I do without being commanded what others do only from fear of the law." - Aristotle
I truly believe that our modern society needs Law. Laws are guidelines that set out appropriate behaviour, so we are required to follow this system of rules, in order to keep everything balanced and stabilized. Without the fulfillment of these desired tasks, man simply will become equal to animals – or worse still, allow their darker sides to emerge and control their lives.
Legal Systems of the World
For this purpose every country has a certain system that the all citizens are required to obey: up to date there are about two hundred countries in the world and each of them makes its own Legal System that is based on certain characteristics and factors of the country. The Legal System consists of certain laws and rules that shape the citizen’s morality and behaviour in the society. There are many academic terms describing what “legal system" is but from my point of view the best one is the description by J.H Merryman:
“A legal system is an operating set of legal institutions, procedures, and rules." 
The three most widespread Legal Systems are: Continental Law Legal System, Common Law Legal System and Religious Law Legal System. Each of these legal systems is unique and has its own specific features and individual structure. Let’s take a brief look on each system and see how systems differ from each other or discover their similarities.
Common Law Legal System
History, sources and structure
The common law system prevails in Britain and its former colonies, including Australia, Canada, and the United States. Traditionally, the common law system, as the name implies, was governed not by a code, but by court-made law that developed incrementally over time. It is different from the civil-law system, which is introduced mostly in Europe and in areas colonized by France and Spain.
The body of decisional law based largely on custom as declared by English judges after the Norman Conquest of 1066. The common law doctrine of following precedent, known as stare decisis remains an important component of both the English and American legal systems today. English common law was based primarily on custom, tradition, and precedent rather than a formal written legal code. Over centuries of experience, the common law became the major influence on the development of American criminal law both before and after the American Revolution. After the Revolution, the common law continued to be the basic law of most states. However, today almost all common law principles and rules have been enacted by legislative bodies into statutes with modern variations. ). One of the interesting characteristics of the system is that the common-law system allows judges to look to other jurisdictions or to draw upon past or present judicial experience for analogies to help in making a decision. This flexibility allows common law to deal with changes that lead to unanticipated controversies. At the same time, stare decisis provides certainty, uniformity, and predictability and makes for a stable legal environment. Under common law, all citizens, including the highest-ranking officials of the government, are subject to the same set of laws, and the exercise of government power is limited by those laws. The judiciary may review legislation, but only to determine whether it conforms to constitutional requirements  .
Civil Law Legal System
History, sources and structure
Civil law may be defined as that legal tradition which has its origin in Roman law, as codified in the Corpus Juris Civilis of Justinian  and it is used mostly in European and Asian countries. It is divided into two branches: the codified Roman law and uncodified Roman law. Civil law is highly systematized and structured and relies on declarations of broad, general principles, often ignoring the details  .
The Differences and Similarities between the Legal Systems
Common Law and Continental Law have similar aims: to protect individuals, to maximize freedom and control the process of following legal rules. A major difference between the civil law and common law is that the doctrine has the greatest priority over other sources of law, while in common law the judge-made precedent is the base of its law.
The civil law doctrine’s function is to extract from cases the rules and the principles which will clarify and punish the crime actions, and thus provide the courts with experience and guidelines for the remedies of some cases in the future. The civilist focuses rather on legal principles. He or she traces their history, identifies their function, determines their domain of application, and explains their effects in terms of rights and obligations. At this stage, general and exceptional effects are deduced. Apart requiring some statutory analysis, determining the area of application of a principle involves some induction from the existing case law, while delimiting exceptions involves some deduction  . Common law jurisprudence sets out a new specific rule to a new specific set of facts and provides the principal source of law, while civil law jurisprudence applies general principles, and that jurisprudence is only a secondary source of law of explanation. Civil law judgments are written in a more formalistic style than common law judgments.
Civil law decisions are indeed shorter than common law decisions, and are separated into two parts – the reasons and the order. This is because civil law judges are especially trained in special schools created for the purpose, while common law judges are appointed from amongst practicing lawyers, without special training.
The method of writing judgments is also different. Common law judgments extensively expose the facts, compare or distinguish them from the facts of previous cases, and decide the specific legal rule relevant to the present facts. Civil law decisions first identify the legal principles that might be relevant, then verify if the facts support their application. While the civil law principles, frozen into codes and often rigid doctrine, are imposed on courts, most common law rules can be changed from time to time, subject to the doctrine of stare decisis  .
Criminal Law and Civil Law
There are two branches of law: Criminal Law and Civil Law. That means that when a person breaks any law, he or she may be judged according to what branch of law it is.
Criminal Law those laws for redressing public wrongs that injure society in general and Civil Law those laws for redressing private wrongs to individuals. Civil law attempts to right a wrong, settle a dispute, or honor an agreement. The victim is being compensated by the person who is at fault, this becomes a legal alternative to, or civilized form of, revenge. Criminal law consists of two main branches -- substantive criminal law and procedural criminal law. Substantive criminal law prohibits certain forms of conduct by defining what acts constitute crimes and establishing the parameters of penalties. Procedural criminal law regulates the enforcement of the substantive criminal law, the determination of guilt, and the punishment of those found guilty of crimes.
Criminal lawsuits differ from civil lawsuits in that the criminal prosecutions are intended to convict and punish the offender, while civil lawsuits are intended to settle disagreement between private parties. The convicted defendant in criminal actions may be fined or may be punished by imprisonment by the government. Civil Law determines private rights and liabilities, whereas Criminal Law concerns offenses against the authority of the state. 
Criminal Procedure and Civil Procedure
Criminal Procedure. The branch of the criminal law that deals with the processes by which crimes are investigated, prosecuted, and punished. Thus, procedural criminal law is the process followed by police and the courts in the apprehension and punishment of criminals from the filing of a complaint by a member of the public or the arrest of a suspect by the police, up to the time the defendant is sent to jail, or, if convicted, to prison.
Civil litigation that deals with private disputes between parties is subject to the rules of civil litigation, sometimes referred to as civil procedure. Criminal cases, deals with acts that are offenses against society as a whole, such as murder and robbery, as subject to the rules for criminal law, and is also known as the rules of criminal procedure.