[sgp_]

Obviously not legal advice, but FinCEN's guidance is quite easy to follow here:

https://www.fincen.gov/sites/default/files/2019-05/FinCEN%20...

> Providers of anonymizing services, commonly referred to as “mixers” or “tumblers,” are either persons that accept CVCs and retransmit them in a manner designed to prevent others from tracing the transmission back to its source (anonymizing services provider), or suppliers of software a transmittor would use for the same purpose (anonymizing software provider).

> An anonymizing services provider is a money transmitter under FinCEN regulations. The added feature of concealing the source of the transaction does not change that person’s status under the BSA.

> An anonymizing software provider is not a money transmitter. FinCEN regulations exempt from the definition of money transmitter those persons providing “the delivery, communication, or network access services used by a money transmitter to support money transmission services.” This is because suppliers of tools (communications, hardware, or software) that may be utilized in money transmission, like anonymizing software, are engaged in trade and not money transmission.

Another resource: https://www.perkinscoie.com/en/news-insights/anti-money-laun...

[jdmichal]

> Providers of anonymizing services, commonly referred to as “mixers” or “tumblers,” are either persons that accept CVCs and retransmit them in a manner designed to prevent others from tracing the transmission back to its source (anonymizing services provider), or suppliers of software a transmittor would use for the same purpose (anonymizing software provider).

How does that not make Monero itself liable as an "anonymizing software provider"?

[sgp_]

Well, you see what FinCEN says about those:

> An anonymizing software provider is not a money transmitter. FinCEN regulations exempt from the definition of money transmitter those persons providing “the delivery, communication, or network access services used by a money transmitter to support money transmission services.” This is because suppliers of tools (communications, hardware, or software) that may be utilized in money transmission, like anonymizing software, are engaged in trade and not money transmission.

In simple terms, the Monero developers are providing software (the Monero network, nodes, and wallet software) that can be used for money transmission, but the developers do not need to register as MSBs unless they also have a side company that conducts money transmission.