all police forceses will know well in advance of any new laws been debated after all they have to impliment them.but it cuts both ways they had knowledge why before that law came in are they then that stupid as to wait 2 or 3 months before it comes in and destroy the evidenmce i dont think so .if they wanted to destroy any evidence they would have done early way early.so no consripcy theorist years later can come and make it look like it was done on pupose only 3 months before the new law
Why would the police get informed of new laws months earlier ? They would not need to implement any new laws until the day it became law. So don't need months of warning.
Maybe a week beforehand , once it has gone through parliament and an exact date has been made all police will be informed.
But it is a good point, if they were somehow aware months earlier, either as the norm or through a tip off, why not destroy the items months earlier ? They could then claim they knew nothing about the upcoming new law and have more chance of being believed.