Sketching People in Public

Interesting opinion about the ethics of sketching people in the New York Times July 25 2014 by Chuck Klosterman:

Sketched Out on the Subway

I was sitting next to someone on the subway who was surreptitiously sketching portraits of fellow commuters. I once spotted someone opposite me doing this, and actually changed cars when I suspected he was eyeing me as a subject. Being present in a public space does not seem akin to offering permission to record your likeness without consent, despite the intended (lack of) audience or purpose of the final piece. Unlike being captured in a tourist’s random photograph, this act seems to involve a level of scrutiny, focus and invasiveness that makes me uncomfortable. Is it ethical to draw someone without his or her permission or knowledge?
-CHRISTIANA MAVROMATIS, BROOKLYN

Part of what makes this question compelling is your discomfort with an act that most people view as vaguely flattering (which is not to say you should be flattered by this — I’m just noting that it’s something people seem to like). I certainly understand your argument and your desire to be left alone. But I still wouldn’t classify this practice as unethical for two reasons.
The first point is that having your image drawn against your will is not the same as being photographed against your will. A photograph is generated by a machine that uses optical technology to capture your actual likeness. It is literally a one-to-one depiction of who you are at a specific moment (unless the photographer uses additional technology to distort it). But a drawing is always interpretive. It’s not really you; it’s someone’s artistic construction of what she believes you look like (and if the artist is into something like Cubism, it might not resemble you at all). You possess the rights to your image, but you don’t possess the rights to what someone thinks you look like. Now, if we were debating the commercial rights to your image, everything changes: If the artist were slapping your face on a bag of potato chips, a photograph and a recognizable drawing can be viewed interchangeably. But that’s not the problem we’re dealing with, nor is it your central concern. We’re just considering the ethical difference between capturing your image with a machine and interpreting your image by hand, and the difference is significant.
The second point has to do with the aspect of the experience that you find most unsettling: the “scrutiny, focus and invasiveness” of the artist’s eye. Basically, you’re saying you don’t want anyone looking at you with this level of intensity. But the sketch is secondary to this. Someone could stare at you with “scrutiny, focus and invasiveness” even if he had no intention of drawing your picture. (Someone could also avoid looking at you completely while taking your photo.) If you’re in public, people are allowed to look at you. This can be creepy and annoying, but it’s not unethical. If the individual scrutinizing you starts sketching your face, you can say, “Don’t do that,” and the person should stop (out of normal human courtesy). But the act is not inherently unethical. 
-CHUCK KLOSTERMAN