After having decided that North Carolina could not tax a trust based solely on residence of a beneficiary in the Kaestner Trust case, the Court had to decide what to do with another case. Shortly after the North Carolina Supreme Court ruled against the North Carolina Department of Revenue in the Kaestner case the Minnesota Supreme Court ruled against the state of Minnesota’s ability to impose its tax on a trust on different grounds.
On June 28, 2019, the Court decided not to hear the Minnesota Department of Revenue’s appeal of the Minnesota Supreme Court’s ruling in the Fielding case. The Minnesota Supreme Court ruled that the state could not impose an income tax on a trust when the only connection with Minnesota was the fact that the settlor had been a Minnesota resident when the trust became irrevocable.
The fact that the U.S. Supreme Court decided not to hear the case does not mean the Court is taking the position that the decision was the correct one, just that the Court has chosen not to hear that particular case. The U.S. Supreme Court has full discretion regarding which cases it does and does not hear.
Thus, at this point while Minnesota is barred by its highest court from imposing a tax on a trust in such a situation, other states with the same rule that have not had their highest court strike down the law will be able to continue to collect the tax (at least for now).
 https://www.supremecourt.gov/search.aspx?filename=/docket/docketfiles/html/public/18-664.html, retrieved June 29, 2019
 Ed Zollars, “Two States Find Their States’ Statutes for Taxing Trusts Violate Due Process Clause,” Current Federal Tax Developments, July 19, 2018