What positions did the United States take in its amicus brief on Aviall (PDF)?
Among other things, the United States took the position that, based on the plain language of CERCLA § 113(f)(1), a party that is itself liable or potentially liable may seek contribution under that section only during or following a civil action under section 106 or section 107, and conversely, that section 113(f)(1) does not authorize a contribution action in the absence of an ongoing or completed section 106 or section 107(a) civil action. The United States also stated that a liable party is limited to seeking contribution in the manner authorized by section 113(f), and that CERCLA § 107(a) does not provide an independent basis for a liable person to recover response costs from another liable person.