According to Evrovizija.com, the rule which refers to the language that the song in EMA (National Selection of Slovenia) can be deposited (free choice of language), is about to change.

From now on, in EMA 2018, all the songs will be in the Slovenian language or in a Minority Language of the country (Croatian, Serbian, German, Hungarian, and Italian).  What we don’t know so far is if this rule will be enforced only for EMA 2018 or and for Eurovision Song Contest 2018. The National broadcaster of Slovenia makes this change after the results of ESC 2017, where Portugal was the winner with a song in Portuguese and other countries like Italy, Hungary and Belarus that used there National languages also got a spot in the Grand Final Show.

Slovenia’s best result was in 1995 and 2001 both 7th place. In 1995 it was Darja Švajger with a song in Slovenian Language (“Prisluhni mi” (“Listen to me”)) and in 2001 represented by Nuša Derenda with a song in English Language (Energy).