We're presently working with a number of clients on reducing their workforce. There are a number of organizational development issues related to a RIF (such as who stays, who goes, what does the company look like after the reduction and how will all the tasks continue to be done).
But there are a number of compliance issues as well.
Baker Donelson has a good piece on some of those pitfalls.
A reduction-in-force is not simply "let's eliminate 'x' number of positions"; it takes careful decision making; excellent organizational development consultation; and a good employment attorney.