In 1961, Knut Grotrian-Steinweg (b. 1935) joined the company. In 1966, the company formed a contract with Wurlitzer to sell Grotrian-Steinweg pianos in the US, and the Steinway company brought suit in New York. The case lasted nine years, winding its way through trial courts and district courts, presenting the litigants' counterclaims and appeals. In 1975, the United States Court of Appeals for the Second Circuit heard the arguments in Grotrian, Helfferich, Schulz, Th. Steinweg Nachf. v. Steinway & Sons. Grotrian-Steinweg, the plaintiff, argued that their brand was long established, predating Steinway's in Germany. Steinway & Sons, defendant, counterclaimed that their brand, well known and strongly positive in the US, was weakened by consumers' confusion as to whether the pianos were related. The court affirmed the lower court's ruling in favor of the defendant that piano buyers would be misled in their "initial interest" in the two piano brands; "a potential Steinway buyer may satisfy himself that the less expensive Grotrian-Steinweg is at least as good, if not better, than a Steinway." The court felt that Grotrian-Steinweg—a brand not very well known in the US—was unfairly given an extra measure of credibility based on the strong reputation that Steinway & Sons had built. Even though premium piano buyers were understood to be sophisticated and knowledgeable, and would not be confused at the time of purchase about which manufacturer produced which piano, the court held that a "subliminal confusion" might be present at the initial attraction to the Grotrian-Steinweg brand. The company was forbidden to sell pianos in the US under the name "Steinweg" after 1977. Accordingly, in 1976 Grotrian-Steinweg formed a subsidiary brand for selling pianos in North America: Grotrian Piano Company GmbH.
