Sure. It's a loose terminology for a group of anti government protestors. They have very bizarre beliefs about the law, don't have licenses or license plates or insurance, file vexatious lawsuits and commit "paper terrorism" on the courts, have fake license plates on their cars, don't pay taxes and try to pay bills from what they think is a secret government trust established in their names at birth worth 2 million dollars. They are quite notorious for getting pulled over for their fake plates, where they refuse to get out of their car and ask repeatedly 'am I being detained ", and end up with their windows smashed and being dragged out of their cars. There are a million videos of this on YouTube and they're quite something.

Here is an article about a notorious case where the cops actually killed one as they thought he had a weapon. It's quite unfortunate but the cops have been killed by sovcits before..

https://www.vice.com/en/article/g5yxw9/utah-sovereign-citizen-chase-allan