It's not legal (yet) to make you share with other people directly. A little bit of inflation will have you sharing indirectly, though.
This protection of your pension account is why OJ was able to keep his pension, btw.
Yet, is the operative word. The Rat's like Jesse Jackson have already proposed a " one time" 20% tax on retirement accounts. I'm sure they have lots of other creative ideas to steal the money. All of course in the name of "fairness".