House Atreides is a mostly composed-of-Humans noble extended family within the Interplanetary Neo-British Kingdom.  They control a number of hereditary positions in government on Caladan and Arrakis and a handful of hereditary seats in the House of Lords on Neo-Britain.  The common people on Caladan and Arrakis are permitted to select local councils, planetary councils, and representatives in the House of Commons by direct popular vote. 

House Atreides is well-known for being a voice of the common people.  It is such populist sentiments that have kept the Atreides in the same league as House Hawkwood, House Decados, House Lihalan, House Hazat, House al-Malik, House Corrino, and House Harkonnen and above the status of the Minor houses.