The law of karma, says only this: `for every event that occurs, there will follow another event whose existence was caused by the first, and this second event will be pleasant or unpleasant according as its cause was skillful or unskillful.‘
Therefore, the law of Karma teaches that responsibility for unskillful actions is born by the person who commits them.
“Karma is the law of moral causation.
In this world nothing happens to a person that he does not for some reason or other deserve. Usually, men of ordinary intellect cannot comprehend the actual reason or reasons. The definite invisible cause or causes of the visible effect is not necessarily confined to the present life, they may be traced to a proximate or remote past birth.
According to Buddhism, this inequality is due not only to heredity, environment, “nature and nurture”, but also to Karma. In other words, it is the result of our own past actions and our own present doings. We ourselves are responsible for our own happiness and misery. We create our own Heaven. We create our own Hell. We are the architects of our own fate.
A moral supportive (kusala upathambhaka) Karma assists in giving health, wealth, happiness etc. to the being born with a moral Reproductive Karma. An immoral supportive Karma, on the other hand, assists in giving pain, sorrow, etc. to the being born with an immoral reproductive (akusala janaka) Karma, as for instance to a beast of burden.” -Ven. Mahasi Sayadaw