Part 1 of Clause 24 of the Immigration Law: 

Paragraph 2: 
Spouse of a Latvian citizen or Latvian non-citizen, or a foreigner who has received a permanent residence permit, as well as the minor children of the spouse; 
Paragraph 3: 
Parents of a Latvian citizen or Latvian non-citizen and their spouses; 
Paragraph 6: 
A foreigner who was a citizen of Latvia on 17 June 1940 or one of his or her parents is a Latvian citizen, and who takes up permanent residence in Latvia; 
Paragraph 7: 
A foreigner who has continuously resided in the Republic of Latvia with a temporary residence permit for at least five years directly prior to the day of submitting the application;