There is nothing in the laws on hashing passwords.
The only requirement is retention of passwords or data permitting to check or change them.
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
"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