Q278
What authority is there that can extend its sphere of action over all the Churches?
A bishop has authority only within his own church. Matters of importance to several or all of the Churches are discussed and decided at gatherings of bishops: councils, or synods, when these are permanent structures.
When a council is gathered, each church is represented by its bishop, which is why, in the ancient canonical order, only active diocesan bishops participate with a deciding voice; in some cases, an entire region is represented by its metropolitan, archbishop, or patriarch. An ecumenical or pan-Orthodox council can therefore make decisions with the widest sphere of application.