It is called Civil Forfeiture wherein law gives power to the law enforcement authorities the power to seize your property in the SUSPICION of illegal use. Note the word suspicion not actual wrong doing.
One of the loops in the code is that police authorities are allowed to keep the seized property (100% in some states like DE, TN), including cash, and do not have any burden of proof.
There is a report that shows grading of the Civil Asset Forfeiture by State. The grading system ranges from A through F where grade A graded State(s) requires criminal conviction before property can be forfeited and incredibly there are only two states with A grade in the entire US.
If you live in an F grade State, like Delaware, the authorities do not have to prove the conviction nor do they need to catch you in any kind of illegal activity, all they need as basis is ‘suspicion’ to seize the property involved including car, home and cash.
You can read the State by State grading and their meaning in this report
https://www.scribd.com/document/267761329/Civil-Asset-Forfeiture-Grading-the-States#fullscreen&from_embed
The map in the report shows that most of America is miserably failing in reforming the Civil Forfeiture laws.
And another incredible map in this context is this one that shows how the bounty is distributed between Federal and State authorities:
If that doesn't bother you, this stat should. According to endforfeiture.com, "About 87 percent of federal forfeitures were civil, not criminal, so the government did not have to charge or convict anyone to take property."
I am not a lawyer and when I learned about this civil forfeiture, I figured lot of people don’t know about it either and is worth knowing obscure part of laws of the State you may be living in.
Source and additional references:
Picture source: http://ij.org/report/policing-for-profit/grading-state-federal-civil-forfeiture-laws/
https://www.law.cornell.edu/uscode/text/18/981
http://www.washingtonpost.com/sf/investigative/2014/09/06/stop-and-seize/
http://www.newschannel5.com/news/newschannel-5-investigates/policing-for-profit/timeline-policing-for-profit