Since they're in the Throne Speech, why not talk about them?
I was invited to a Facebook group against all mandatory minimum sentencing because it doesn't prevent crimes and, the group alleges, is used by governments to play up and encourage peoples' fears of crimes even in the face of decreases in the incidence of crime.
The general idea behind mandatory minimum sentencing is to make the perceived expected cost of a crime greater than the perceived expected benefit of a crime to a potential criminal, and in this way make it seem unprofitable and therefore deter them from committing said crime. Expected costs can be made higher in two ways: higher chance of getting caught (more cops), or higher costs (fines, jail time, insurance premiums, etc.)
Apparently there have been studies done (there have - Google it) and in a lot of cases (though not all) mandatory minimums have had no measurable effect on the occurrence of crimes. (Specifically drug crimes, but some others as well.)
Now, obviously I'm opposed to minimum sentencing for drug charges, because I'm opposed to drugs being illegal and that any jail time, let alone mandatory minimums, does significantly more to ruin someone's life than possession or use.
I'm also opposed to mandatory minimums for an accessory details to a crime, such as the presence of a gun with the criminal... if someone is committing a crime what they're doing it with should not really matter - what matters is that they're doing it and the extent of the harm that they cause.
But let's assume that the studies are right, and that mandatory minimums are unlikely to prevent a crime - what if that crime is very serious? For instance rape, murder, and perhaps theft over a certain amount. In these cases, I think that punishing someone for extensive harm to another person, even if it doesn't necessarily justify mandatory minimums, it certainly makes them understandable.
Maybe I'm missing something, but the only reason I can see for blanket opposition to mandatory minimums is a reaction to their overuse.
cross-posted to The Natural Society