Landmine charity: Ban the killer robots before it's too late!
They're already here, chum - look around
The killer robots, in this sense, are already widespread.
In any case, the idea that having a human in the loop will necessarily make for a weapon less prone to accidentally slaughter innocents seems hard to support. This is particularly the case when the human's own personal life may depend on a threat being eliminated quickly and certainly. A robot can be programmed to calmly accept the risk that failure to open fire may mean its own destruction; humans often tend to prioritise their own survival over absolute moral righteousness, no matter what instructions they may have been given.
Thus, the difference between the quick and the dead when up against an armed and dangerous enemy often leads soldiers and policemen to shoot or blow up people they shouldn't. A robot could well, in fact, be better at applying rules of engagement which may feel - may actually be - suicidal if followed strictly by human operators.
Even where the human isn't personally at risk, he or she is no panacea regarding the right call getting made. Rage, hatred, over-excitement, unwillingness to allow enemies to escape, simple stress or tiredness - all these can lead the controller of a remote system to be far more bloodthirsty than a correctly programmed autonomous one. It's also been noted many times that those who kill remotely are significantly less prone to freeze up on the trigger than those who must watch their victims die in front of them; so safe remote humans aren't necessarily better than frightened sweaty ones. There are no simple answers here.
And even the most righteous, unworried human still won't do any better at deciding whether or not to shoot unless there is some information which people excel at interpreting - for instance video or still images of people who may be armed or unarmed. Humans do well with certain kinds of images; that proficiency doesn't mean that they bring anything to the party when all you have is other kinds of data. It doesn't mean the absence of humans in the loop always makes killings unacceptable.
We here on the Reg killer-robot desk maintain a guardedly open mind regarding autonomous lethal systems. We don't especially welcome our new killer robot overlords, but we don't propose to panickily (and probably ineffectually) legislate them out of existence either. The more so as - in this sense - they're actually already here, and have been for at least a hundred years.®
*Readers may not be surprised to note that this piece of international law hasn't been universally followed during recent sea mining campaigns in the Persian/Arabian Gulf. Not that the miscreants in question had ratified the Hague Convention anyway.