Comment 31 for bug 312536

Here are a few more details about that API.

The able to policy bits would be initialized when NSS is initialized.

It would have no persistence. Each time NSS is initialized, the
application must then make any changes to the policy table that it wishes
to make.

To disable MD5 for use in certs, the application might use this code:

SECStatus rv;
rv = NSS_SetAlgorithmPolicy(SEC_OID_MD5, ~NSS_ALG_USABLE_IN_CERT_SIGNATURE, 0);