For auto policy, how much liability coverage do I need?

My current auto policy is due to expire, and I notice that for the policy renewal, the insurance company (AXA) has reduced the third-party liability coverage on the per-person bodily injury benefit from 1 million baht to 500,000 baht. This concerns me, and the broker won't offer any advice about the amount of coverage that I should have. But it begs the question: how much coverage do I really need? I'm not a bad driver, but I worry that I could find myself without much financial protection in a lawsuit situation. Anybody have any insights on this?

I've been renewing the same policy, with the same broker, for something like 10 years now, and this is the first time I've noticed an effort to reduce the benefits.

Thanks for any feedback!