A US judge has rejected a request by Samsung Electronics to lift a ban on US sales of its Galaxy Tab 10.1, dealing a third legal setback to the South Korean firm in just a week, as it braces for a make-or-break patent trial later this month with Apple Inc., Reuters has reported. Apple sued Samsung last year, accusing the South Korean electronics maker of "slavishly" copying the iPhone and iPad. Samsung denied the claim and countersued. The case is due to come to court this month and could have implications in other jurisdictions. The two companies have gone to courts in around 10 countries, accusing each other of patent violations as they vie for supremacy in a fast-growing market for mobile devices.