There are nuances. Most exactly, if I can prove I am a priest, they must allow me to celebrate Mass in the church. But it does not have to be a specific Mass or a public Mass. They can give me a side altar at 7:00am if they really want, but it is usually easier just to allow me to concelebrate.
Does canon 903 really say they must let you concelebrate?
There are nuances. Most exactly, if I can prove I am a priest, they must allow me to celebrate Mass in the church. But it does not have to be a specific Mass or a public Mass. They can give me a side altar at 7:00am if they really want, but it is usually easier just to allow me to concelebrate.