That is, when an official is involved in a lawsuit in their official capacity, why does the case name not refer to the title of the office, given that the incumbent can change during the course of the trial? (As we have seen with Perry v. Schwarzenegger becoming Perry v. Brown.) Why is it Roe v. Wade and not Roe v. District Attorney of Dallas County? And, on the other hand, why is it Brown v. Board of Education and not Brown v. (some people)?
I suppose this is partly just legal tradition and might not really be answerable, but I’d still be interested in hearing about the topic.
I think it probably depends on both the state and the case. For example, I know that in my state , state agencies have no existence separate from that of the state and must be sued in the Court of Claims, while if I am sued in both my “individual and official capacity” , that case can proceed in the regular trial courts. The case can also be dismissed against me as an individual while proceeding against me in my official capacity, and I presume it is also possible to go in reverse- dismissed as an official but continuing against me as an individual.
Sovereign immunity. As a general matter, you can’t sue governments unless they waive immunity. So, you sue the relevant state official(s) instead. For tort purposes (like, you sue your city because you were run over by a city bus), the state law governing sovereign immunity waiver will require that you sue the state or subdivision in a particular capacity.