How does ICANN delegate IP addresses?

Question

Computer networks

In the introductions of almost all textbooks or articles on networks, there is a passing mention of ICANN, whose role is in the distribution and management of root DNS and the delegation of IP address spaces to providers. It is clear that the highlight is in the link layer and tunnels like IPv4 <-> IPv6 - everything else varies either from connection to connection (at the physical level) or depends on the needs of hosts \ clients \ peers, in short, it is very replaceable by users - even traditional DNS can implement in a communist way and in the manner of bitcoins (in its simplest form - as a distributed database with PGP-signed instructions from the owners on how to resolve the host).

Another thing is the link layer, on which everything is always tied - even if we use a tunnel to a different link layer.

Actually the question, which, for ease of understanding, I will put practically: how does ICANN (the organization) order the network to reject, say, the greed of some tier 1 provider that occupied an address range recently purchased by another provider? (Intrarectal heat transfer to network system administrators is not considered authority.)
Can the first provider actually occupy someone else's address range?
What role do backbones play in the drama?

Answer 1

But no way. Only papers.
If tomorrow Rostelecom blows 8.8.8.0/24 on BGP to everyone on its own behalf, then all its peers will think that it is. Another question is that peers can filter such garbage. But if Rostelecom is the only uplink for someone, then it is unlikely that announcements from it will be filtered.
All routing in the world is built on the trust of major backbones to each other and the exchange of their announcements.
Such are the things.
UPD: related link - uinc.ru/news/sn21508.html ;)