Digital dollars are perfectly legal for American fiat banks

Bank manager have authority to act as trustees over an account.

Any bank client can ask the trustee to put their account on the stable coin ledger using he trustee agreement, perfectly legal, The trustee agreement only allows withdrawals that also updates the stable coin ledger. The provable contract is a public proof of stake ledger managed inside the solidify code.

In fact, any fiat bank can use this ledger or any other equal stable coin ledger managed by another fiat bank. The account moneys flagged as stable coins must be taken off  reserve status, that is all the central bank need to see.

There is nothing for central banks to do to create stable coins, they can already exist.  No new technology, we already have working stable coin contracts in Solidify. No new law needed.

These stable coins work just like check writing, and merchants have the responsibility to manage fraud by keeping the ledger up to date. Merchants can hold stable coin transaction, and clear accounts at the end of day for folks they trust. 

Thus, we do not have bearer asset, yet.