Skull Pilot continue to assert that there is no law against walking around with cash. Sadly, that isn't true. Having large amounts of cash - defined as $100 or more - IS considered suspicious activity and it can be seized even if you haven't done anything wrong. People use cash for all sorts of purchases. For instance, I used to work at trade shows where people bought many products in cash. The vendor ends up with lots of cash on-hand but, because they are traveling between states, can't deposit that cash in their regular bank account. I personally have carried thousands in cash when returning from a trade show.
Here is some legal background:
Forfeiture takes two distinct forms -- criminal and civil.
Nearly all contemporary forfeiture involves the civil variety. Criminal forfeiture operates as punishment for a crime. It, therefore, requires a conviction, following which the state takes the assets in question from the criminal.
Civil forfeiture rests on the idea (a legal fiction) that the property itself, not the owner, has violated the law. Thus, the proceeding is directed against the res, or the thing involved in some illegal activity specified by statute.
Unlike criminal forfeiture, in rem forfeiture does not require a conviction or even an official criminal charge against the owner. This is the source of its attractiveness to law enforcement, and its threat to those concerned about abuse or circumvention of Constitutional protections.
Categories of Property Subject to Forfeiture--Bennis v. Michigan 517 U.S. 1163 (1996) (Stevens, J., dissenting)
1. Contraband
Property for which ownership by itself constitutes a crime, including smuggled goods, narcotics, and automatic weapons. The government's mandate in protecting the public forms the justification for seizure in this case.
2. Proceeds from Illegal Activity
Property directly resulting from, or that can be traced to, an illegal activity. Once a crime is identified, the government may seize any property flowing from the activity. In some cases, the government may seize property in lieu of provable criminal proceeds. Statutory innocent owner defenses provide a check on the seizure power, although this burden lies with the owner, not the government.
3. Tools or Instrumentalities Used in Commission of a Crime
Property used in the commission of a crime, including vehicles and real estate. By being associated with the crime, the property is "guilty" of the offense, and subject to seizure. In some cases, the innocence of the owner may not be a defense, although Constitution limitations, such as the Eighth Amendment's Excessive Fines Clause, may apply.
LII Backgrounder on Forfeiture