> I did three group assessments, and out of those three failed two students with the help of my teammates, by co-ordinating our peer assessment. This peer assessment does not become public until grades come out, at which point they can be disputed. But 3 vs 1 usually comes out in favour of the group.

This is, inadvertently, fantastic training for sociopathic stack-ranked office politics.

> RE the group assignments, my university quite successfully dealt with this by introducing a scaling factor based on peer assessments within the group.

This is something my university has done, but didn't implement quite as well. I think the key here is making it completely anonymous (ideally filled out online individually) because otherwise objectively assessing a group member's performance in front of them is difficult.

With that said, I think I'd still find it hard to outright fail a group member via these means unless they literally put zero effort into the group project - it seems a small thing to threaten their entire degree over.

I failed a group member over this. They did put a small amount of effort in, but the problem was that the parts of the project they agreed to take on ended up having to be done or re-done at the last minute. If we had just known he was going to do nothing, we at least could have planned for it. In the end, putting in that small amount of effort actually hurt more than putting in none at all.