What mandatory minimum sentences do is handcuff the ability of trial judges to give what they feel is the appropriate sentence for a particular offender.
What we know from the empirical evidence is that members of racialized communities are overrepresented in the criminal justice system. They are arrested disproportionately to their representation in their community. They're convicted. They're sentenced for longer periods of time. What mandatory minimum sentences do is force judges to send these particular members of the community to jail, even when, outside the mandatory minimum sentence, they wouldn't have to go to jail.
The reality is that these members of these marginalized communities may not have the resources to fight mandatory minimum sentences and the challenges in the courts, so they end up getting a sentence that they otherwise would not have received.
Bill C-5, through introducing discretion to trial judges, will hopefully alleviate the problem of overrepresentation.