Surely it is true that the majority of attorneys have a rudimentary understanding of their country's laws, the notion that any lawyer could memorise every statute in its entirety is absurd. For starters, much of the globe is governed by the common law or a derivative of it in some form or another. The result is that lawmakers draught broad legislation, and courts interpret that law in individual instances, so establishing norms for later cases to follow.
There are sometimes thousands of decisions issued each year in even the smallest jurisdictions, making it hard for a lawyer to keep up with every single change. To the best of his or her ability, a lawyer can comprehend the principles of the law and remain abreast of major cases that indicate alterations in the laws of their or their clients' professional areas.
And, after a case has been identified, time is spent undertaking in-depth research, if and when appropriate. However, even in civil law nations, the majority of bodies of law are so extensive that no one can possibly know everything; as a result, attorneys often strive to become experts in certain fields rather than generalists.
To give an example from the United States, nearly all American law students study criminal law, civil process, contracts, torts, property law, and constitutional law, among other subjects. After that, people can choose from a variety of electives (such as environmental law, antitrust, tax, securities, administrative law, international law, and so on) that are tailored to their own interests.
Most courses are electives, which means it is possible to graduate from law school and become a qualified lawyer without ever having studied or learned anything about a variety of legal topics. The bottom line is that at the time when you graduate from law school, you are familiar with the fundamentals of law in a variety of professions. You are absolutely not knowledgeable about everything, though; you are just familiar with the essential norms and how key instances have been interpreted and implemented.
Just about any student who graduates from law school could tell you how a contract is made, the elements of a negligence claim, the rule regarding felony murder, and what the rule against perpetuities is, but they are scarcely specialists in any particular discipline. Once you graduate from law school & begin working in the field, you will begin to specialise in a certain area of the law.