kiwi1: The Tabingo and Emam groups are both mandamus cases, that's why applicants who have filed with Tim and with a Tabingo lawyer were asked to choose which case to keep alive. Keeping both could be seen as forum shopping (in any case, the judge could exclude cases for which a decision has been made). The difference is the time frame, which is why the Tabingo group had to fight s87.4 along the way. Had the Tabingo group succeeded at the FC level, without DoJ appealing, the decision on s87.4 would have covered all affected FSW backloggers, while the decision on mandamus would have only covered the Tabingo group.
st-cnncomes: Mandamus cases are lawsuits against delay. I can't answer about the fraud, because CIC only acts according to laws and regulations. I see it more as a fight against Parliament when you're looking at the fraud angle. As for suing against delay in refunds, you'll probably get a refund before you can get a FC decision.
I did read the Tabingo decision, and I believe Justice Rennie did not dig deeper into the data on PR based on country of origin and the backlog. Every year CIC sets the quota ("targets", they say) or maximum number of visas for each visa office. If there was really no discrimination, much larger targets would have been allocated each year to countries with bigger backlogs than those with none, to even up the backlog. It would be completely undiscriminatory if FSW processing times across all visa offices were at 24 to 36 months, rather than have some at zero backlog and others at 80+ months.