Some companies have a limit on the number of times you can work for them, in order to prevent people from hopping and coming back for more money. I think a previous company I worked at had a limit of 2 employment periods, which they instituted (supposedly) after a large number of people took voluntary separation and then came back later after the company started growing more. The next time a voluntary separation came up the policy was implemented to prevent another round of that happening.
This seems equal parts petty and self-defeating to me.
No one except the worst performers are going to stay at a place when they see market salaries rising substantially everywhere else. So what this does is hamstring the company from re-hiring the top performers who could easily get new, higher-paying jobs at other companies.
Equally bad is that the weak employees will have gained substantial organizational power, so they'll be making decisions by virtue of time served instead of skill and knowledge.
I know of one case where a manager avoided that clause by bringing the person back again as a full-time contractor, which effectively doubled the previous salary...
