Is Google Glass legal to use?

There seems to be a lot of misinformation going round about privacy concerns of Google Glass. Congress doesn't seem to understand, fellow Verge-goers seem to be in dispute...let's try to tackle these concerns with the laws already in place for cameras. Keep in mind I'll back up any of my opinions on the subject with reasoning and evidence, but please feel free to engage in constructive discussion.

http://www.aclu.org/free-speech/know-your-rights-photographers

"When in public spaces where you are lawfully present you have the right to photograph anything that is in plain view." There is no expectation of privacy in a public place, you don't need permission to have or use a camera in a public place. Keep in mind there is a difference between exercising your right to photograph in a public space and harassment.

The line between legal and illegal is very blurred and is often up to interpretation. I believe you can mitigate the risk of confrontation by considering the intention of the photographer, the sophistication of the equipment used, and the expectation of privacy.

Examples of videos where the photographer has questionable intentions (and where I would draw the line at harassment in the public area):
http://www.youtube.com/watch?v=h_2zfPJACXY http://www.youtube.com/watch?v=qeS0PBmUK_Y You can't follow someone around with a camera and not expect any consequences, likewise, photographing children is a very shady area legally speaking.

An example of video where sophistication of equipment drew unwanted attention can be seen here. His discussion around 13:00 is very interesting about how police officers told the photographer he needed to get a permit to photograph a public building he was shooting with a Gigapan. Why did the police allow him to continue to shoot without the permit? Would the police have confronted him if he was just using a DSLR? Would he still need to get a permit if he wasn't using the footage for commercial reasons (say a school project)?

I am not certain about the law behind using photos of people in public for commercial reasons (and I'm sure it varies), but I doubt Glass users will use it for anything but personal use. The argument of how "subtle" Glass is compared to a cell phone should be irrelevant.

Expectation of privacy is the simplest one for me to understand. I should be able to photograph you if I'm walking around Time Square because we're both in a public area. But some public photography is illegal, for example voyeur or upskirt videos are definitely illegal because there is a clear expectation of privacy (law seen here). Now what about TSA's magic-camera that they can use to undress you to find a bomb or a gun?

Glass in private areas is no different than a cell phone or camera: the owner of the property can ask you to stop, if you don't comply, they can ask you to leave

Videos with audio are NOT treated the same way as pictures and video w/o audio (wiretapping laws get sticky). Some states require both parties (the person recording and the person being recorded) to consent before you can start recording. Other states just require one party to consent.

In short, you shouldn't have any problems legally when using Glass as long as your motives aren't nefarious (spying on other people). Understand what areas public and private and if there's an expectation of privacy or not. Research to see if your locality has any special laws regarding privacy or photography. And don't act like you have anything to hide or are doing anything wrong!

If someone asks me to stop photographing them in public, I would stop even though I'm not legally obligated to. I'll stop not only to avoid the possibility of getting knifed, but if I didn't stop, my motives would be put into question and I might be seen as harassing. However, I would under no circumstances delete any photos that I already took.

There are of course certain people who claim "MUH PRIVACY" without any attempt to hear you out. They do not understand the law and they usually do not respond to reasoning or logic. The best course of action is to ignore, not engage in discussion, and calmly walk away.