Just the words "High Crimes" means nothing.
You need to be specific in the crime and its punishment.
Murder = ?
Sexual Assault = ?
Assault = ?
Corruption = ?
Being an ass = ?
Now what standards will you use for lets say Sexual Assault? It is usually a his vs her version. Did he/she take advantage of a situation or not? In a case where there was an attack and a Sexual Assault occurred do you have the forensics to back up a claim? What do you do if it was a false claim?
A lot of things going on here. Say they made a false claim to get out of a sticky adultery situation? Does that person then get punished? What if it was an unwanted advance with say touching. Does grabbing the buttocks rate death versus maybe a set period of rehabilitation work?
What are the laws right now in the 196 countries covering Sexual Assault? What constitute Sexual Assault?
It isnt an easy oh they were convicted of Sexual Assault and must be shot out the airlock.
I would take a set of laws already in place, redefine them for the situation of being in space and make the punishment fit the crime.
Justice and security will be the tough areas to nail down