One issue is that if the police find evidence of a crime during the investigation of another crime, then they are bound to pursue the newly found crime too [0]. Under such dragnets, which you can nearly 'grep' for crime, many more totally innocent people can be found to be felons without their knowledge. 2011's Three Felonies a Day by Silvergate and Dershowitz [1,2] is a good launching point into issues with the US federal justice system. If you'd like to learn more, Ken White's twitter is a great place to start the learning process into law's foibles [3].
[0] Under many complex and often conflicting legal codes, this is admittedly a dubious statement. Add in budget issues and whoo-boy, might as well throw dice. But, in general, this is mostly true. Also, I am not a lawyer, consult your own lawyer.
[1] https://www.amazon.com/exec/obidos/ASIN/B00505UZ4G/ref=nosim...
[2] https://www.popehat.com/2018/12/18/alan-dershowitz-is-lying-... The book is HOTLY contested and Dershowitz may or may not be an insane person