Cash is private. When you spend cash, there’s no paper trail. Cash transactions are difficult, if not impossible to trace.
Because it’s difficult to track cash transactions, the US government over the last 35 years has quietly enacted civil forfeiture laws that make it possible for police to confiscate cash or other property with near-zero evidence of any wrongdong. The states have followed suit with their own civil forfeiture laws, mostly modeled on US statutes. And even if a state lacks its own confiscation law, state agencies can use federal civil forfeiture laws to confiscate cash or other property and receive a kickback of up to 80% from the federal government.
When the government seizes your property under a civil forfeiture law, it doesn’t need to prove you did anything wrong. All it needs to do is to demonstrate, by a preponderance of the evidence, is that your property is subject to forfeiture.
Cash is particularly vulnerable to this argument, because US courts have repeatedly ruled that possession of a large sum of cash is "strong evidence" of a connection to trafficking in illegal drugs. In other words, merely possessing a large sum of cash provides the government with sufficient evidence to seize it, unless you can provide clear and credible evidence that it’s NOT connected to illegal drugs.
And even then, you might still lose it, as illustrated by the confiscation of US$124,700 from three motorists in Nebraska, recently upheld by the Eighth Circuit Court of Appeals. During a traffic stop, Nebraska state troopers asked permission from Emiliano Gomez Gonzolez, the driver of a rented vehicle, to search the car. Gonzolez gave them permission, and during the search, the troopers found bundles of cash totaling $124,700. Later, a drug-sniffing dog, "alerted" to the presence of narcotics residue on the money.
Based on this "evidence" of narcotics related activity, police seized the currency, but released the driver and his two passengers without filing criminal charges. (This is despite the fact that numerous scientific studies have demonstrated that more than 90% of US currency is contaminated with narcotics residues—see http://www.cocaine.org/cokemoney/index.html for an example.)
Gonzolez contested the forfeiture, and at trial, testified that after pooling his own legitimately earned cash with that of two partners in the produce business, he flew to Chicago to purchase a refrigerated truck. Both partners’ testimony backed Gonzolez’ account of the legitimate source and intended use of the defendant currency, which the government never contested.
The trial court believed Gonzolez’ story and ordered the cash returned to him. But on appeal, the Eighth Circuit Court of Appeals overturned the trial court’s decision and awarded the money to the government. The government never convicted or even accused any of the owners of the seized currency of any drug-related crime. Police never found any drugs, drug paraphernalia, or drug records connected to the seized currency.
While not all federal courts have ruled the same way in similar circumstances, the handwriting is most definitely on the wall: if you possess a large quantity of cash—certainly any amount exceeding US$10,000—you are inviting police to confiscate it as the probable proceeds of a narcotics transaction. And the government doesn’t need to arrest you or present any evidence of narcotics involvement in order to prevail in court.
What this means is that you should never carry or store large quantities of cash in the US. Police can "legally" seize it and you have very little recourse. It might (or might not) help if you withdraw newly manufactured bills (which would presumably not contain drug residues) from your own bank account and keep the withdrawal slips with the cash to prove its legal origin.
But the trend is clear. The US government and police agencies throughout the US have declared an undeclared war on cash. And any cash you carry or store, legally or otherwise, is in their sights.