Some time ago, I wrote a column headlined: "What Is a DB Pension Really Worth?"

The main idea was simple: Conservative retirement planning should assume most (defined benefit) pensions will not pay out 100 percent on the promised dollar. The column offered guidance on how to help clients evaluate the soundness of their pension promises based on the sponsor's financial health, plan type and funded status.

If I were writing the same column today, I would be more pessimistic about DB pensions. A provision of the recent Cromnibus legislation, known as Kline-Miller, has quietly overturned a 40-year-old pillar of U.S. pension law. It will allow distressed multiemployer DB plans to slash benefits previously protected by ERISA, to avoid insolvency and eventual takeover by the Pension Benefit Guaranty Corp.'s nearly-broke multiemployer plan. The legislation, which probably was necessary to avoid even greater distress for pensioners and taxpayers later, may be a harbinger of broader cutbacks in both public and private DB plan benefits.