Question:
The real question is what constitutes "post roads"? Do the phone lines
and cables through which e-mail travels count as post roads? Could
Congress assert authority over ISPs the same way it can over delivery
services?
Answer:
-The "law" at issue is the US Constitution, Article One, Section 8:
The Congress shall have power to... establish post offices and post
roads.
It's called the postal monopoly clause. Basically, companies and
services like UPS and FedEx exist at the pleasure of the federal
government. If Congress wanted to exert its power using the postal
monopoly, it could order them shut down.
Realistically, it's highly unlikely that such a thing would ever happen
and if it did, there'd be years of lawsuits, probably all the way to the
Supreme Court, but the technical power is there in the law for the
government to do it.
-To say that it is "against the law" was admittingly a bit broad, but
the intent is still intact. It does enjoy a government-enforced
monopoly over letter mail service so competition is nil. As a
quasi-government agency, it does have the regulatory power to enforce
this monopoly aggressively. As has been mentioned, the USPS
encompasses the right to exclusive use of your mailbox. Since it is a
not-for-profit group, it can be $11 billion in debt with no worries.
