It's because it will make your legislation more certain, but it will raise a question in respect of other legislation if it's amended to state this, because now other legislation will be looked at, and a court interpreting it could say, well, yes, the Canada Labour Code says that it applies, notwithstanding any other act.
But when we look at the proposed Aeronautics Act, it also says that, so that's clear. But this other statute--I'll pick one off the top of my head, rail or something--that doesn't have that type of clause, if there are court proceedings to interpret that legislation, the Aeronautics Act amendment may have created an uncertainty for the court in how to interpret other legislation.
There's a lot of legislation that the Canada Labour Code takes precedence over, and the Department of Justice hesitates to see any uncertainty raised in what is now considered to be a fairly certain matter.