The obedience experiment conducted by Stanley Milgram in 1963 has become widely known for its sociological and psychological implications. It's difficult to assign positive or negative values to it as it's often regarded as an experiment with unexpected and shocking results. People asked to administer electric shocks to others responded in a variety of ways. While no actual electric shocks were administered (actors playing the "test subjects" faked their responses), the participants did not realize this. When the administrators of the experiment asked participants to increase the voltage on the shocks, some participants balked and refused, while others agreed. Each time the participants were asked to increase the voltage slightly, they were made aware that they did not have to oblige. The experiment was intended to measure the participants' likelihood of obeying authority figures in contexts where other people might be harmed. Comparisons to the Nuremberg defense have often been mentioned regarding the Milgram experiment.
The positive impact of the experiment is the realization that people are more swayed by authority figures than would be expected. But its possible that individual personality types (less empathetic, for example) would continue to participate because their concern for other people is less than those who refused to administer pain. The negative impact of the experiment is the possibility that the results could inspire authority figures to use similar tactics in situations where people are not able to leave, i.e. incarceration or hostage situations.