Technology workers and trade groups representing American workers have joined together to fight a little known visa category they claim is costing American technology workers their jobs. In the last three years, the use of L-1 visas has risen 40 percent, as firms bring in foreign workers as part of a strategy to cut labor costs. The L-1 visas were intended to allow companies to transfer employees from a foreign branch or subsidiary to company offices in the United States. However, they are now routinely used by companies based in India and elsewhere to bring their workers into the United States and then contract them out to American companies - often as replacements for American workers. Professor Steve Yale-Loehr, Cornell Law School, said that what these companies are doing is legal, though perhaps not what Congress intended. Just this month, Rep. John L. Mica introduced a bill this month to prevent companies from hiring foreigners with L-1 visas.