Google's claim that it will not need to alter its privacy policy to reflect the impact of its new Glass product has been met with scorn by US authorities.

Senator Joe Barton, who co-founded the congressional bi-partisan privacy caucus, sent a detailed letter of concern to Google in May asking the company to clarify how Glass users' data would be protected, as well as the privacy of non-users who could be identified through technology including facial recognition.

In a lengthy reply, Google's vice-president of public policy and government relations, Susan Molinari, emphasised that Glass is in a trial phase, that there are no plans for facial recognition to be introduced and that existing privacy policies will protect users and non-users.

Barton was not impressed, releasing the following statement on Monday night: "I am disappointed in the responses we received from Google. There were questions that were not adequately answered and some not answered at all.

"Google Glass has the potential to change the way people communicate and interact. When new technology like this is introduced that could change societal norms, I believe it is important that people's rights be protected and vital that privacy is built into the device. I look forward to continuing a working relationship with Google as Google Glass develops."

Molinari deftly avoided a specific question about the fallout from the revelation that Google had inadvertently captured personal information from individuals on unencrypted wireless networks while gathering data for its Street View project. Barton had asked how Google planned to prevent Glass unintentionally collecting data without consent.

"Protecting the privacy and security of our users is one of our top priorities," Molinari wrote, but then deferred on an answer to the next question about protecting privacy more broadly.

Molinari did make some details public about improvements to privacy features for Glass, including ways to lock the device if it is stolen.

Eyes are on Google to set a standard of good practice for the wearable technology as multiple devices start to come to market. Its biggest challenge will be to balance the opportunities for the technology and those keen to explore it, with those who see insurmountable problems with a more invasive technology that has implications for the people that come into contact with it as well as the person wearing it.

As the security researcher Marc Rogers told Slashgear last month, the challenge is around expectation. The first wearable computer was developed by the maths professor Edward O Thorpin and Claude Shannon in the 1960's to cheat on roulette tables.

"People weren't expecting someone to be able to take a computer into that environment," said Rogers. "Who's to say what Glass will allow? Industrial espionage, identifying flaws in buildings, scoping out security positions. It would be easy to modify Glass to identify every single security camera, and plot you a path you could walk through a shopping centre where you're not going to be recorded."

"What Glass has done is draw people's attention to new concepts. So, if people are talking about the risk of Glass, in reality that risk has been around much longer. It's just Glass is making you think about it."