A July 7 NewsBusters post by Warner Todd Huston called a claim that Fred Thompson worked as a lobbyist for a family-planning group in the early 1990s "hearsay" and "an unproven (and maybe unprovable) claim." Huston further asserts that there's "no real proof by anyone here. A casual reading easily makes the "evidence" against Thompson seem stronger than that in his favor... even though both are just a she-said/he-said claim."
In fact, the Los Angeles Times article that reported on the claim cites "the minutes of a 1991 board meeting of the National Family Planning and Reproductive Health Assn." as evidence and names five people as corroborating the claim.
Huston seems to have a funny definition of "unproven (and maybe unprovable)."