Inheritance Tax in Iowa

Few states have inheritance taxes any more, but Iowa still does. A recent court case there illustrates that the Iowa law has a strange provision.
A handful of states have an inheritance tax either in addition to or instead of a state estate tax.
Inheritance taxes are similar to estate taxes. With an estate tax, the estate itself is taxed before distribution to people. With an inheritance tax it is the tax is assessed on the people inheriting the estate.
Iowa is one of the states with an inheritance tax. However, it has an exemption for the tax when it comes to children who inherit from their parents. However, Iowa changed that exemption...