leave (something) to (someone's) discretion

Translations
оставить (что-то) на усмотрение (кого-то)
The choice of color is left to the designer's discretion.
Выбор цвета оставлен на усмотрение дизайнера.
Definitions
To allow someone to make a decision or judgment about something based on their own judgment or preferences, rather than imposing a specific requirement or directive.