This idea is important as ameans to prevent UK laws being passed without due debate and legal passage into UK law. In the past British versions of EU Directives have become mere vehicles for contentious legislation that was judged incapable of being legislated for by normal Parliamentary means. British versions of Directives contain very different provisions to those passed in other EU states.
Note: this issue only concerns Directives, it does not apply to EU Regulations and Decisions as these cannot be corrupted as with Directives.
This law-making abuse is difficult to detect and uncover as the legisslation is usually nodded through as EU law carrying the added measures into law and beyond the power of recall and revision by the UK Parliament.
A lot of legislation from Europe has been unfairly blamed for creating legilative overload on, e.g., Health and Safety and REACH legislation that is different from that of other EU jurisdictions and is a heavy and uneccessary administartive and cost burden created solely by British politicians.
This is a serious matter that is long overdue for attention. In fact the solution lies with the UK Parliament, not Brussels in this instance of Directives and their passage into each state's domestic law.