WASHINGTON, Sept 10 (Reuters) - U.S. lawmakers determined to tighten antitrust laws said on Friday that a judge"s decision giving only a partial victory to "Fortnite" creator Epic Games in its fight with Apple Inc (AAPL.O) was further evidence of the need for new laws to limit Big Tech. Earlier on Friday, a U.S. federal judge struck down some of Apple"s App Store rules, forcing the company to allow developers to send their users to other payment systems in a partial win for Epic and other app makers. read more U.S. Senator Amy Klobuchar, chair of the Senate Judiciary Committee"s antitrust panel, said the ruling addressed only some of her concerns about app stores. "We need to pass federal legislation on app store conduct to protect consumers, promote competition, and foster innovation," she said in a statement. In a briefing with reporters, Apple"s general counsel, Katherine Adams, defended the company"s practices, saying they benefit iPhone users by protecting their privacy. "Rather than limiting innovation or competition, the App Store has turbocharged it, ensuring that every developer has an opportunity to compete," she said. Klobuchar had teamed up with fellow Senate Democrat Richard Blumenthal and Republican Senator Marsha Blackburn to introduce a bill in August that would bar big app stores, like Apple and Alphabet Inc"s (GOOGL.O) Google, from requiring app providers to use their payment system, among other measures. read more U.S. Representative Ken Buck, a Republican, along with a Democratic colleague, introduced a similar measure in the House. Buck and Blackburn said in a joint statement that the ruling was a step in the right direction but agreed it showed why their bill was needed. "Apple has abused their power to bully and profit off small companies," they said in a joint statement. "All businesses should be able to communicate with their customers and not be held hostage by monopolistic behavior." House Judiciary Committee Chairman Jerrold Nadler and Representative David Cicilline, chair of the antitrust subcommittee, also called for tougher antitrust laws following the ruling. The House Judiciary Committee voted in June to approve six bills to tighten antitrust law, four aimed directly at Big Tech. "It is clear that courts continue to narrowly interpret the antitrust laws in favor of monopolies," they said.