Where the theories of damages for a class of plaintiffs match the theory of liability, class certification is appropriate. The 7th U.S. Circuit Court of Appeals reversed a decision by U.S. District Judge Harold A. Baker, Central District of Illinois. Purchasers of organic asphalt roofing shingles across the country filed suit against IKO Manufacturing, arguing that IKO falsely told customers that its shingles met an industry standard known as ASTM D225 and that compliance with the standard was ascertained through a …