John Schmidtlein, a partner at Williams & Connolly LLP who is representing Google in a  high-stakes antitrust trial in Washington said Google was selected because it delivers value to them, not because they have to.

"Users today have more search options and ways to access information online than ever before."

Schmidtlein pushed back on claims by US Justice Department antitrust enforcers that Google has used its market power -- and billions of dollars in exclusive deals with web browsers -- to illegally block rivals.

Users have choices, and it's easy to switch, he said. For example, Microsoft pre-selects its own search engine, Bing, on Windows PCs, yet most PC users switch to Google because it's a better product, he said.

Web browsers offered by Apple and Mozilla, which makes Firefox, have long chosen a default search engine in exchange for a revenue-share that helps pay for innovations, Schmidtlein said.