I could be wrong, but the laws are very ambiguous on this. I have no issues with private insurance. With Mainecare, most have to have a digital signature. Federal law also mandates that I either fax, call in, or use tamper proof scripts for any script including antibiotics. With private or self pay, I don't have these restrictions. I can also fax in without a signature Paragoric, Lomotil, Vicodin, Tylenol with codeine to some pharmacies but not others. The DEA person I spoke with is rather confused on this issue.
But, I had issues AFTER the Mainecare law came out ONLY because pharmacies were much more vigilant. They simply told me to write Electronically signed or Digitally singed, and they would be OK, which is rather silly as it means nothing without two certificates or keys on both ends.
Hope this helps.