environmental clean-up at the Douglassville site was discharged in the § 77 reorganization. Reading is not liable to the United States under § 107(a)(4)(A), and Reading is therefore not a “person who is liable or potentially liable under [§ 107(a) ] of this title,” 42 U.S.C. § 9613(f)(1). Conrail’s claim for contribution under § 113(f) fails as a matter of law. At oral argument, Conrail mentioned for the first time that it had spent over $1 million on remedial measures at the Doug-lassville site. Because of the lateness of Conrail’s assertion of any such direct expense, we will not analyze the nature of Conrail’s claims to ascertain if Conrail is in fact asserting a claim that is more than one for contribution. See, e.g., United States v. Voigt, 89 F.3d 1050, 1064 n. 4 (3d Cir.1996) (<HOLDING>). For that reason, we do not need to consider
holding failure to brief argument constitutes waiver holding that failure to brief an argument constitutes waiver holding that failure to raise an issue until it is brought up at oral argument constitutes a waiver holding that failure to raise issue in brief constitutes waiver of appeal of the issue holding that appellants failure to raise preemption argument until posttrial motions constitutes waiver of defense