If a plaintiff is from out of State, it is sometimes wiser to sue a Trust in Federal Court, as described in Wills, Trusts & Estates Prof Blog in "Trustee Citizenship Regulates Federal Diversity Jurisdiction."
The plaintiff in the article was a citizen of Taiwan suing a Trust that her ex-spouse set up. While it is not clear why she did not want to sue in State court, she did choose to file suit in Federal court.
One way to get jurisdiction in Federal court is called diversity jurisdiction. For it to apply, the plaintiff and the defendants have to be residents of different States or Countries. In this case, the court decided that diversity jurisdiction was appropriate based on the citizenship of the Trustee.
Reference: Wills, Trusts & Estates Prof Blog (Dec. 14, 2016) "Trustee Citizenship Regulates Federal Diversity Jurisdiction."