I do not think the company will win in a situation like these, they can stop the transactions that were not withdrawn, other than that there is no way they are going to get that kind of amount back if the customers already withdrew the coins and threatening with legal actions will not mean anything and it is their million dollar blunder.
I have a different opinion in this case. Laws of most countries, including the US where Blockfi was incorporated, has a 'doctrine of unjust enrichment'. The underlying principle of this doctrine is that a person cannot become richer at the expense of the other (i.e. without any consideration). For example, if you deposit $100 into your neighbor's account by mistake, you can recover the $100 from the neighbor and such a deposit does not result in a valid contract or gift. You can read up more on unjust enrichment here:
https://www.law.cornell.edu/wex/unjust_enrichmentBlockfi's case can be analyzed in parts to be better understand the legalities:
- Recoverability as per law: Here in this case, if Blockfi is able to prove that the accountholders had become unjustly richer at the expense of Blockfi (which seems to be the case here), they can move the court for recovery of the amounts. On the basis of doctrine of unjust enrichment, the courts are likely to allow Blockfi to initiate recovery proceedings against accountholders
- Identification of Account holders: Blockfi makes it mandatory for each account holder to provide their KYC documents and hence would have the data of the account holder. Hence, identifying the account holders and tracing them should not be a hurdle (unless the account holder has provided a fake ID or is absconding).
- Actual recovery from account holders: Once the account holders are traced, Blockfi would have to obtain the bitcoins or equivalent fiat currencies or assets from the account holders. However, if the account holder has spent all or most of the money received from Blockfi; in such cases Blockfi may not be able to recover any assets from the account holders and such attempt maybe futile (even if recovery is legally allowed)
- Overseas account holders: The final leg is the case of overseas account holders. In their case, even if Blockfi initiates the cases, the respective nations of the overseas account holders may not extradite or allow enforcement of US law in their soil. In such cases the recovery is virtually impossible.
Therefore, though it is legally allowed for Blockfi to be able to recover the money from the account holders, it will have a lot of practical hurdles to do so.
Hope the above is able to provide more perspective on this issue. Would be happy to have your comments on this. Thank you.