There is a political battle on now as in 1999 as IBM with the support of US industry is trying for a retroactive law change so as to make what they have done with their pension plan legal
I do not like converting a defined benefit plan to defined contribution and calling the result "cash balance". If you want to screw the older workers it is quite legal to do so - you should just not be allowed to pretend you have not screwed anyone.
While the tax court ruled Onan's plan should be disqualified for age discrimination against older workers as defined for defined benefit plans,
http://www.careerjournaleurope.com/columnists/edchoice/19991228-schultz.html , the WSJ report DEC. 28, 1999 (Page A1) noted that the 1991 decision to put into the preamble to the 91 regulations words that imply a "safe harbor" sentence -Specifically, the sentence stated that a pension plan's accrual features "will not cause a cash balance plan to fail to satisfy the requirement of section 411(b)(1)(H)." This means that the preamble implies that while the rate at which benefits build up in cash-balance plans declines with age, employers don't have to worry that they are violating age-discrimination law, so per the WSJ, cash-balance plans were all installed "in perfectly good faith, and the IRS never followed through with regulations."
And while a preamble does not have force of law, the IRS is now faced with the question of whether to insist that all cash balance plans comply with the defined benefit version of the age-bias law -- or whether to endorse the 1991 sentence saying cash balance plans are safe from this law.
Unfortunately for the IBM workers, there is a historical parallel that would suggest IBM will ultimately win. In a dispute involving insurance companies that manage pension money that reached the Supreme Court, the insurers argued that for 20 years, they relied on a sentence in a Labor Department bulletin that seemed to exempt them from fiduciary requirements under pension law. And in 1993, the Supreme Court said, essentially, tough luck -- the sentence didn't have the force of law. Insurers and employer groups then sought a legislative rescue, and Congress provided one. It in effect overturned the high-court decision and insulated pension sponsors retroactively from employee lawsuits.
Sounds a lot like where we are now.