The June 22, 2011 PC Magazine article by  Chloe Albanesius (“Congress, Google Clash Over Schmidt, Page Appearance”) includes the following excerpt:

Several groups were all in favor of the subcommittee using a subpoena. “What are Page and Schmidt afraid of? What do they have to hide? Congress should use its subpoena power to determine whether Google’s dominance of the search industry is enabling the company to monopolize the Internet,” said Consumer Watchdog’s John Simpson.
“A vibrant, competitive marketplace is essential to consumer welfare, and testimony from Google leadership will provide legislators with answers and a better understanding of the marketplace,” said Steve Pociask, president of the American Consumer Institute.