When registering a domain you are bound to follow the terms and policies associated with the domain in question:
.SE Rackfish information page for .SE domains (terms, integrity policy, and more): svenska
IIS registration terms and integrity policy for .SE-domains
.NU registration terms and integrity policy
.EURid terms, registration policy and whois-policy
.UK Nominets terms
Other:
ICANN's terms (mandatory contract clauses)
ACSIO policy