Under which circumstances physical punishment to wife is allowed?
As Medhātithi explains, it's only allowed under exceptional conditions.
What is enjoined here is the method of keeping the persons on the right path, and not actual beating; so that chastisement may be administered verbally; and in cases where the fault is serious, there may also be beating.
‘Split bamboo’ — the bark of the bamboo. This has been mentioned only as illustrative of the lotus-fibre and other such objects which cause only slight pain. — (299)
Also, Manu 8.300 says:
But only on the back part of the body, and never on the upper part; he who strikes otherwise than this incurs the guilt of a thief. — (300)
So slapping one's wife or kid on their face (as they portray in some Indian movies) is not allowed. A husband/father/teacher who violates this maybe reported to the authorities.
Yama (Vivādaratnākara, p. 2.). — 'Wife, son, slave, slave-girl and pupil, — when these commit a fault, they should be chastised with a rope or with split bamboo; but in the lower, never in the higher, parts of the body :— if one strikes them otherwise, he should be punished.'
Nārada (Do.). — 'If the pupil docs not obey the teacher, he should be chastised, without hurting him, either with a thin rope or with split bamboo; the teacher shall not beat him much, nor in the head or on the chest. Behaving otherwise than this, the teacher should be punished by the King.'
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