If a defect was pointed out in a statutory instrument, I would consider that a matter for stopping it going forward. Most of the arguments I have heard in recent times do not point to
any mistake in an instrument. They are more theoretical. I do not wish to examine them in detail—I have done that once—but it is important. That is what was proposed when these instruments were originally laid. It is much easier to amend an instrument by taking it back and starting again than with an Act of Parliament. That is the appropriate procedure for correcting a defective instrument, and it happens, not necessarily formally, but quite often instruments are withdrawn when a mistake is pointed out; they get round to writing it again and hopefully the second time it is improved.