Within a few decades autonomous robotic devices, computing machines, autonomous cars, drones and alike will be among us in numbers, forms and roles unimaginable only 20 or 30 years ago. How can we be sure that those machines will not under any circumstances harm us ? We need a verification criterion: a test that would verify the autonomous machine’s ‘moral’ aptitude, an aptitude to make ‘good’ rather than ‘bad’ choices. This paper discusses what such a test would consist of. We will call this test the ethical machine test or the Just Machine Test (JMT).  The Just Machine Test is not intended to prove that machines have reached the level of moral standing people have, or reached the level of autonomy that endows them with ‘moral personality’ and makes them responsible for what they do.