In its antitrust confrontation with the government, the pillar of Google’s defense has been that innovation — not restrictive contracts, backed by billions in payments to industry partners — explains its success as the giant of internet search. From a report: Its competitive advantage, it says, is brilliant people, working tirelessly to improve its products. Pandu Nayak, Google’s first witness in the antitrust trial that began last month, is the face of that defense. Mr. Nayak, a vice president of search, was raised in India and graduated at the top of his class at one of that nation’s elite technical schools. He came to America, earned his Ph.D. in computer science at Stanford University and then spent seven years as a research scientist on artificial intelligence projects at NASA’s Ames Research Center in Silicon Valley.

Nineteen years ago, Mr. Nayak joined Google and found a particularly welcoming workplace, filled with professional friends. “At the end of the day, Google is a technology company — it really values the skills that I have,” Mr. Nayak said in his testimony on Wednesday. The computer scientist’s testimony is an attempt to rebut a central argument in the case filed by the Justice Department and 38 states and territories. Their suit claims that scale is essential to competition in search. That is, the more data from user queries a search engine collects, the more it learns to improve its service, which attracts still more users, advertisers and ad revenue. That flywheel, the suit says, is fueled by ever-increasing volumes of user data.