In Jain ethics, ahimsa (non-violence) is the highest principle. But it is not a simple rule about “not stopping” harm at any cost; it is about the intention, the means, and the karmic consequences of our actions.

Key points:

• Non-violence is about your own thoughts, speech, and deeds. Causing harm to another living being is karmically binding.
• If you can prevent a killing without harming the killer or by using non-violent means (calling for help, restraining the person safely, creating a distraction, alerting others), that is in line with ahimsa.
• If stopping the killer inevitably requires you to inflict violence, the karmic outcome depends on intention and necessity. Jain ethics generally favors minimizing violence and seeking non-violent resolutions; violent acts carry heavy karmic weight.
• Self-defense is a nuanced topic in Jainism. It is ideally guided by the aim to protect life while avoiding harm as much as possible. The more one can reduce suffering through non-violent means, the better.

Practical guidance:

• Seek help from others, authorities, or bystanders to neutralize the threat without using force yourself.
• Use calm restraint and de-escalation; prioritize saving lives over proving a point.
• If violence is unavoidable, act with the least possible harm and with a clear intention to protect life, not to retaliate or cause suffering.

If you’d like, I can explain how different Digambar and Shwetambar interpretations approach the dynamics of ahimsa in life-threatening situations, or point to traditional Jain texts that discuss non-violence and restraint.