What is the Office of the Keys?
The Office of the Keys is that special authority which Christ has given to His church on earth to forgive the sins of repentant sinners, but to withhold forgiveness from the unrepentant as long as they do not repent.
Where is this written?
This is what St. John the Evangelist writes in chapter twenty: The Lord Jesus breathed on His disciples and said, "Receive the Holy Spirit. If you forgive anyone his sins, they are forgiven; if you do not forgive them, they are not forgiven."
What do you believe according to these words?
I believe that when the called ministers of Christ deal with us by His divine command, in particular when they exclude openly unrepentant sinners from the Christian congregation and absolve those who repent of their sins and want to do better, this is just as valid and certain, even in heaven, as if Christ our dear Lord dealt with us Himself.
That is an interesting citation, particularly considering that (so far as I understand), Lutherans do not consider Holy Orders in the same way that Catholics do (as a sacrament).
But it didn’t answer the specific questions: is there an accepted code of Canon Law within LCMS that provides standardization of the legal process (to include excommunication)? Also, is there some variety of an appeals process?