[bduerst]

Exchanges could but they definitely don't have a black list of dormant/fraudulent addresses somewhere.

These people could also tumble the bitcoins, where they convert it to an alt coin or other currency before converting back to a different address. That's how money launderers currently use bitcoin now and bypass the whole "public record" thing.

[IkmoIkmo]

I wouldn't say 'definitely'. I think it's actually quite likely. Some reports have already surfaced of this. Some reports have surfaced about their reporting obligations. Both because they're controversial. i.e. the fungibility of bitcoins is very important for many reasons. The moment we have 'tarred' bitcoins, we get different bitcoins with different histories, and with different values. So a stolen $1 is suddenly worth $0.50, forever, because it's got a blockchain history associated with theft. That is not a workable long-term system, so it has received a lot of backlash from the community, which is why these stories usually get out.

And it's known that many companies do a lot of analysis and tracking and have lists, so the biggest bitcoin company in the world for example (close to half a billion valuation), Coinbase, is known to close down and flag accounts who's bitcoins have been traced to e.g. relatively innocuous sports gambling websites, because of its compliance obligations.

So the notion of black lists is not unlikely. What is unlikely is that (without gov. pressure), they will be eager to employ them. Again, fungibility gets destroyed and bitcoin takes a big hit, might not be workable that way. And two, they cut into their own business to block customers. And three, institutions blocking blacklisted coins goes against the privacy spirit and non-reliance on 3rd party permission of bitcoin, which is something that makes you popular.

It also appears government hasn't asked for this yet and that they prioritise innovation and rapid growth over implementing crushing regulations in a tiny ecosystem. But that might change. Although if this happens (government requiring black lists etc) I think it's more likely that exchanges will get extra reporting duties, allow the sale of bitcoins, and that banks will be the ones freezing the fiat accounts. That'll give the government easily seizable assets, and proof of laundering, yet allows the bitcoin ecosystem to continue on as usual.

[bduerst]

I've seen some rumors about blacklists, but I didn't think anyone took it seriously. All it would take is one exchange to allow the bitcoins to change addresses to defeat the purpose.

The international scope of the exchanges and their competitive nature makes it seem unlikely that blacklists will be successful. Addresses are pretty ubiquitous by design, so short of blacklisting entire exchanges I don't see it working. (Even then tumbling would get around it)