Carole House, a former White House director for cybersecurity and secure digital innovation, who is now executive in residence at Terranet Ventures, spoke at the DeCenter Spring Conference at Princeton University in April, proposing exactly that.

In her speech, House suggested that it would be great if miners, as well as validators of proof-of-stake blockchains, came together and agreed not to mine OFAC-blacklisted transactions, as well as not to build upon blocks with such transactions. She also noted that having as much hashpower as possible in the U.S., where miners have to comply with the sanctions, would help make that vision a reality. 

https://www.theblock.co/post/267759/bitcoin-faces-risk-of-protocol-level-censorship-as-miners-under-increasing-regulatory-pressure

so now they not only don't want people mining transactions on the OFAC list but if they happen to make it into a block they don't want miners to build on those blocks. just wow! 

OFAC is in the USA. The Office of Foreign Assets Control. They want to control everything especially about bitcoin.
 https://ofac.treasury.gov/