Asimov's Three Laws of Robotics are justly famous. But people shouldn't assume that they will ever actually be used. They wouldn't really work.
Asimov wrote that he invented the Three Laws because he was tired of reading stories about robots running amok. Before Asimov, robots were usually used as a problem the heroes needed to solve. Asimov reasoned that machines are made with safeguards, and he came up with a set of safeguards for his fictional robots.
His laws are far from perfect, and Asimov himself wrote a whole bunch of stories taking advantage of the grey areas that the laws didn't cover well.
Let's consider a big one, the biggest one: according to the First Law, a robot may not harm a human, nor through inaction allow a human to come to harm. Well, what's a human? How does the robot know? If you dress a human in a gorilla costume, would the robot still try to protect him?
In the excellent hard-SF comic Freefall, a human asked Florence (an uplifted wolf with an artificial Three Laws design brain; legally she is a biological robot, not a person) how she would tell who is human. "Clothes", she said.
http://freefall.purrsia.com/ff1600/fc01585.htm
http://freefall.purrsia.com/ff1600/fc01586.htm
http://freefall.purrsia.com/ff1600/fc01587.htm
In Asimov's novel The Naked Sun, someone pointed out that you could build a heavily-armed spaceship that was controlled by a standard robotic brain and had no crew; then you could talk to it and tell it that all spaceships are unmanned, and any radio transmissions claiming humans are on board a ship are lies. Hey presto, you have made a robot that can kill humans.
Another problem: suppose someone just wanted to make a robot that can kill. Asimov's standard explanation was that this is impossible, because it took many people a whole lot of work to map out the robot brain design in the first place, and it would just be too much work to do all that work again. This is a mere hand-wave. "What man has done, man can aspire to do" as Jerry Pournelle sometimes says. Someone, somewhere, would put together a team of people and do the work of making a robot brain that just obeys all orders, with no pesky First Law restrictions. Heck, they could use robots to do part of the work, as long as they were very careful not to let the robots understand the implications of the whole project.
And then we get into "harm". In the classic short story "A Code for Sam", any robot built with the Three Laws goes insane. For example, allowing a human to smoke a cigarette is, through inaction, allowing a human to come to harm. Just watching a human walk across a road, knowing that a car could hit the human, would make a robot have a strong impulse to keep the human from crossing the street.
The Second Law is problematic too. The trivial Denial of Service attack against a Three Laws robot: "Destroy yourself now." You could order a robot to walk into a grinder, or beam radiation through its brain, or whatever it would take to destroy itself as long as no human came to harm. Asimov used this in some of his stories but never explained why it wasn't a huge problem... he lived before the Internet; maybe he just didn't realize how horrible many people can be.
There will be safeguards, but there will be more than just Three Laws. And we will need to figure things out like "if crashing the car kills one person and saves two people, do we tell the car to do it?"