"Proportionate punishment" means that the punishment should fit the seriousness of the offense committed. It implies that the penalty should be fair and reasonable, and not excessively harsh or lenient. Full definition
It will be seen in Part IV of this article, however, that this promise of proportionate punishment is fragile. (slaw.ca)
And let us assume now, just for the sake of argument, that losing his job does seem like an appropriate and proportionate punishment for acting like a jerk (or, perhaps, for being one). (canadianbusiness.com)
The 2001 Anti-terrorism Act challenges proportionate punishment by providing for mandatory consecutive sentences for overlapping terrorism crimes. (slaw.ca)