Three US citizens from two different companies have sued Tata Consultancy Services, alleging discrimination based on race and national origin, and are seeking exemplary and punitive damages, in the latest case to bedevil India’s largest IT outsourcing company.  The complaint — filed by Darryl Stacy, Donald Stephen Bradley and Hesham Hafez in the District Court of New Jersey late last month — alleged that TCS prefers to bring in employees on visas even when there are trained US citizens and further discriminates when it hires locally by preferring Indians and South Asians.