Instead of making things even worse than they are at present, the next government should rethink the whole system, which is a complete waste of scarce government funding, says deputy general secretary Leslie Manasseh in an article on the Guardian’s Public Leaders Network website.

He was responding to a call by Maude to move from the current, already flawed system, where managers categorise staff as performing “well”, “acceptably” and “poorly”, to one where employees are individually ranked, allegedly to prevent gaming of the system.

Manasseh says: “Every day I hear members – managers and staff alike – report that the system leads to unfair treatment and exacerbates discrimination against minority groups.”

Prospect first revealed evidence of institutional discrimination against minorities in November last year.

Figures from this April show the pattern continuing, with disabled and older people and those from ethnic minorities more likely to be placed in the bottom category and less likely to be in the top group.

The system is damaging to staff given poor markings – who in the worst cases face “managed exits”.

But it also puts managers in an impossible position, he says. A manager who sat on two moderation panels this year told the union: “In one panel we were ‘lucky’ in that there were a few low-performing staff in the pool and so our 5% requirement was met without issue.

“In the other panel the staff concerned were consistently high performers and it was heart-breaking and more than a little depressing having to decide who should be unfairly penalised.”

• Read the full blog on the Guardian Public Leaders Network website.