In 1997, retaliation claims comprised about 23% of all cases filed with the EEOC. Last year, that number jumped to 32.3%.
Why the increase?
For one, employment attorneys advise that it's much easier to prove retaliation than the underlying cause (say, sexual harassment). While harassment may often boil down to 'he said, she said', retaliation is often black-and-white.
I've conducted workplace investigations where we were convinced there was no harassment, only to find out an employer retaliated against that same employee. In other instances, I've seen an employee's attorney not contest the harassment only to focus on the retaliation.
Robin Shea, writing in Costangy, Brooks & Smith's corporate newsletter, does an excellent job of summarizing the issues with retaliation.