I worked quite awhile in the UAW. Super Seniority was given to union stewards. A person winning a steward job had seniority that was above anyone else on their shift and in their department, only in regards to layoff. They basically had to get rid of the entire shift in that department for that person to be laid off.
We had elections once a year so when layoffs were threatening, only high seniority people would get elected. No one wanted to be displaced by someone with less actual seniority than they had.
Our stewards had to be nominated and run in an election that could only be voted on by their shift and department.