Without a by your leave; without so much as a by your leave

Pro Tip 1/3

Permission Ignored

Used when someone acts without seeking approval first, often leading to surprise or annoyance.

He joined the trip without a by your leave, which baffled everyone.

Pro Tip 2/3

Informality

This phrase is informal and best used in casual conversations, not formal settings.

She entered without a by your leave, as if the house were her own.

Pro Tip 3/3

Disregard

Implies carelessness towards others' opinions or rights in the acted-upon situation.

They started the project without a by your leave from the committee.