Romney eschews responsibility for things that happened at Bain once he ceased to be actively managing the enterprise. He was listed in dozens of SEC filings as "sole shareholder, sole director, president and chief executive officer" of Bain funds involved in corporate investments and takeovers after he left Bain in 1999 to head the Salt Lake City Olympics.

Avik Roy, a Romney policy advisor who used to work at Bain subsidiary Brookside Capital (a hedge fund), weighed in Wednesday at National Review Online:

Which of Bain Capital’s investments is it fair to hold Mitt Romney accountable for? The answer: He is accountable for the investments in which he actually made the decisions. If I have my 401(k) invested in the Fidelity Select Health Care Fund, am I responsible for every decision made by the portfolio manager at Fidelity? Obviously not. The same goes for Mitt Romney.

Journalist David Corn, who has been doing quite a bit of recent investigative reporting on Romney and Bain for Mother Jones, replies to Roy:

This was hardly equivalent to a retirement fund investment. Romney "wholly owned" Brookside, according to a SEC filing. He created this entity. No doubt, he had a say regarding who was managing it. It was part of the Bain world he oversaw. He bears a degree of responsibility — perhaps Romney can calculate the precise percentage — for this venture.

Corn is right that Roy's retirement fund analogy is silly; there's a world of difference in one's connection with decision makers between being one of thousands of mutual fund shareholders and being the sole director and CEO of an investment entity that you yourself helped to create. You get the feeling that Roy himself realizes this, given that he devotes 10 paragraphs following the analogy to a defense of the moral legitimacy of the investments that Romney is supposedly not accountable for.

The surprising thing politically is that Team Obama is focused narrowly on trying to make this into a wonky campaign argument about Romney's role in layoffs and outsourcing, along the lines of, "Look at the economic pain that resulted from Bain investments that occurred when Romney was signing documents as sole shareholder and CEO even though he says he had moved on." That's a lovely but overly complicated narrative. Instead of hitting Romney for irresponsible capitalism, Obama should be hitting Romney for irresponsibility, period. Forget about trying to slice and dice the specifics of what result this or that Bain investment in the early 2000s yielded for this or that factory in the midwest.

Having successfully (some might say masterfully) goaded Romney into splitting these legal hairs on the meaning of his signature on SEC filings, the message should be a straightforward assault on Romney's character, along the lines of: Mitt Romney doesn't believe in taking responsibility for his actions. He signs off as chief executive and then says he had nothing to do with it. This responsibility claim should also encompass the numerous instances in which Romney has changed positions over the years on various issues: He doesn't believe in taking responsibility for his words.

Democrats are accomplished at complaining that Republicans have the upper hand when it comes to messaging that frames an attack in simple, direct terms that everyone can grasp and then repeats it endlessly. Socialism. Taxing job creators. Death panels.

With his signature on dozens of SEC documents, Romney has handed Democrats just such a messaging opportunity. A lack-of-responsibility narrative that marries the Bain experience with Romney's many changes of position gives Dems a chance to do unto Repubs as they have done unto Dems. And it can be done with integrity — there is nothing in such a strategy that distorts or stretches the truth, or removes it from context.