According to the FBI:
Domestic terrorism is the unlawful use, or threatened use, of force or violence by a group or individual based and operating entirely within the United States or Puerto Rico without foreign direction committed against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof in furtherance of political or social objectives. (source)
In Michigan, union protesters physically assaulted Steven Crowder of Fox News, then destroyed a tent belonging to Americans for Prosperity (video below).
The union activity caught on tape involved
- violence and/or use of force
- by a group
- based in the United States
- without foreign direction (that we know of)
- committed against persons (Crowder) and property (AFP)
- to intimidate or coerce the governor of Michigan (government) and members of AFP (civilian population)
- in furtherance of political or social objectives
Therefore, unions – at least those involved in the Michigan terrorism — are terrorist organizations. International unions would seem to be international terrorist organizations.
Funding of terrorist organization is a federal crime. Logically, then, anyone who voluntarily contributes to a union willfully and unlawfully supports a terrorist organization.