In my career I've been laid off and had to lay people off more than once. Choosing randomly seems like a pretty good way of doing it. It eliminates the the decision being made based upon race, sex, religion, marital status, nepotism, sexual orientation, etc. It also removes a bunch of other office politics from the decision. One time I had to fight to keep a high performer over a low performer because the low performer played 3rd base on the company softball team.