Civil-rights groups have said certain ethnic groups have been selectively profiled in the searches by Border Patrol agents and customs officials who have thewithout obtaining warrants or having probable cause.
Companies whose employees travel overseas have also criticized the inspections, saying the search of electronic devices could hurt their businesses.
The federal government says the searches are necessary for national security and for legal action against people who bring illegal material into the country.
"If you asked most Americans whether the government has the right to look through their luggage for contraband when they are returning from an overseas trip, they would tell you 'yes, the government has that right,'" Senator Russ Feingold, Democrat of Wisconsin, said Wednesday at the hearing of a Senate Judiciary subcommittee.
"But," Feingold continued, "if you asked them whether the government has a right to open their laptops, read their documents and e-mails, look at their photographs, and examine the Web sites they have visited, all without any suspicion of wrongdoing, I think those same Americans would say that the government absolutely has no right to do that."
In April, the United States Court of Appeals for the Ninth Circuit ruled that the Customs and Border Protection agency could conduct searches without reasonable suspicion.
In her testimony, Farhana Y. Khera, the president and executive director of Muslim Advocates, said Muslim Americans traveling abroad had often had electronic storage devices seized without apparent cause. She said several had also been questioned about their political views.
Susan K. Gurley, executive director of the Association of Corporate Travel Executives, said the seizing of laptops could hurt people who travel overseas for business.
"In today's wired, networked, and borderless world, one's office no longer sits within four walls or a cubicle; rather, one's office consists of a collection of mobile electronic devices such as a laptop, a BlackBerry, PDA, and a cell phone," Gurley said in prepared remarks.
She said the searches meant that "you may find yourself effectively locked out of your office indefinitely."
Gurley said a concern was the lack of published regulations explaining what happened to data when it was seized and who had access to it.
Tim Sparapani, senior legislative counsel for the American Civil Liberties Union, said in an interview, "You can't go into my home and search my computer without a warrant, but simply because I'm carrying my computer with me as I travel, you can search it."
But Nathan A. Sales, an assistant professor at the George Mason University School of Law, said in a statement: "The reason the home has enjoyed uniquely robust privacy protections in the Anglo-American legal tradition is because it is a sanctuary into which the owner can withdraw from the government's watchful eye. Crossing an international border is, in many ways, the opposite of this kind of withdrawal."
Feingold expressed discontent that the Department of Homeland Security, which oversees the customs and border agency, did not send a witness to testify. He said a written statement by Jayson P. Ahern, deputy commissioner for the agency, provided "little meaningful detail on the agency's policies."
Ahern's statement said that the agency's efforts did not infringe upon privacy and that it was important to note that the agency was "responsible for enforcing over 600 laws at the border, including those that relate to narcotics, intellectual property, child pornography and other contraband, and terrorism."