There are various types of law, and it’s exact make up tends to differ from country to country. It can alter which laws apply and how these were put into place to begin with. Some aspects of law are easier to grasp than others, while it can all be subject to change. Generally though laws are made by governments, and then can be altered by court rulings, and how judges interpret pieces of legislation.
When discussing law in the case of the UK there are several types and ways it can be enacted and sometimes amended. British law has been strongly influenced by the concept of common law. The idea of common law can be traced back to Anglo-Saxon times though it was made systematic during the reign of Henry II. After the Norman Conquest the law had altered yet the the principles of Roman Law had never replaced those of common law. English legal practices gradually spread into Wales after Edward I conquered it.
Essentially since Tudor times Wales has had the same legal system as England with the proviso that documents and court hearings can be in Welsh. That system was put into place in Ireland prior to partition in 1921. The courts and hearings were alerted during the Troubles. Scotland has it’s own legal system, though generally the laws in place are very similar, and again common law is the cornerstone of the system.
Prior to the UK joining the EU legislation passed by Parliament was the most important, but that changed with EU membership. British law can be overturned by EU directives and regulations, whilst the European Court of Justice and the European Human Rights Convention can both force legal changes with their respective rulings. Should British voters back the Leave campaign in the EU referendum that could all change.
A UK exit from the EU would have major legal implications, which would not be fully known until after the event. Currently though EU legislators and judges can override British law no matter what Parliament, judges, or the public think about it.
All legislation has to pass through both Houses of Parliament and the Law Lords can rule on controversial laws or pass cases on to the European courts to make a final ruling. The Human Rights Act of 1998 makes it easier for members of the public to take their cases to be heard in Strasbourg as well.