There is nothing in the laws on hashing passwords.
The only requirement is retention of passwords or data permitting to check or change them.
Update:
Hashing is an implementation detail (of something which was not even formulated in question).
I definitely shall be highly surprised if any law would have stipulated technical details of implementation and realization of any principles
Update2:
"Is there any legal reason to save a cleartext password?" here, on the same board, discusses the US FCC requirement to store passwords in clear text