Well, of course the prosecutor has the power not to demonstrate that certain conditions hold, but the point of a mandatory minimum sentence is that Parliament in the year 2011 is saying that some small number of marijuana plants, for example, is deserving of a six- or nine-month minimum sentence. That's what Parliament's intent is. If Parliament didn't have that intent, Parliament presumably would not impose a mandatory minimum penalty. Other kinds of guidance are possible to Parliament, including the guidance of, for example, a presumptive sentence. There are other things that are possible.
On October 18th, 2011. See this statement in context.