In Jain Dharma, the clear principle is:

Killing is never “permissible” in a spiritual sense, even in self‑defence. But Jain scriptures also recognise that householders (shravaks) live in the world and sometimes face unavoidable danger.

1. The ideal principle (for all, and absolutely for monks/nuns)

• Ahimsa is the highest vow.
• To kill, to cause killing, or to approve of killing – all are himsa and bind heavy karma.
• For sadhus and sadhvis, even violent self‑defence is not allowed. They must endure, flee, or accept death, but not retaliate.

2. For laypeople (householders)

For a householder, Jain ethics is slightly practical:

• Your first duty is to:

- avoid the situation if possible, - escape, call for help, shout, run, - use non‑lethal ways to stop the attack (blocking, holding, shutting a door, etc.).

• If, in a rare extreme case, there is truly no other way to save your life or another’s life except an act that may kill:

- Traditional Jain thinkers sometimes call this “virodhi‑himsa” (protective / defensive harm) – the lesser evil compared to letting many be killed. - But even then, it is still himsa, and does bind bad karma. It is not spiritually “clean”; it is only understandable from a worldly standpoint.

Key points for the householder:

• Intention matters:

- Protection, not hatred or revenge. - No enjoyment of violence, no anger or cruelty.

• Degree matters:

- Use minimum force needed to stop the threat. - Aim to disable, not destroy.

• Afterwards:

- Do pratikraman, ask for forgiveness, reflect deeply, and strengthen your vow of ahimsa.

3. Digambar / Shvetambar view

• Both traditions agree:

- Ahimsa is supreme. - For monks/nuns: no violent self‑defence. - For laypeople: life in society unavoidably involves some violence; one must minimize it and never glorify it.

• Some texts (in both traditions) accept that rulers/soldiers may use force to protect others, but this is still karmically harmful, not spiritually ideal.

Simple summary

• Spiritually: Killing is never “allowed” in Jainism; it is always himsa.
• Practically for laypeople:

- Do everything possible to avoid and escape violence. - If absolutely no option remains and life is in immediate danger, defensive harm may be the lesser evil – but it still brings karma and requires repentance and renewed commitment to ahimsa.

You can read a related explanation on ahimsa and being physically harmed here: