▁which ▁remains ▁a ▁member ▁of ▁the ▁EU ▁and ▁the ▁other ▁is ▁a ▁new ▁state ▁which ▁must ▁re apply ▁and ▁be ▁accepted ▁by ▁all ▁other ▁member ▁states ▁to ▁remain ▁in ▁the ▁EU , ▁or ▁altern atively ▁whether ▁both ▁states ▁retain ▁their ▁EU ▁membership ▁following ▁se cess ion . ▁ ▁In ▁some ▁cases , ▁a ▁region ▁leaving ▁its ▁state ▁would ▁leave ▁the ▁EU ▁- ▁for ▁example , ▁if ▁any ▁of ▁the ▁various ▁propos als ▁for ▁the ▁en larg ement ▁of ▁Switzerland ▁from ▁surrounding ▁countries ▁were ▁to ▁be ▁implemented ▁at ▁a ▁future ▁date . ▁ ▁During ▁the ▁failed ▁Scottish ▁independence ▁refer endum ▁of ▁ 2 0 1 4 , ▁the ▁European ▁Commission ▁said ▁that ▁any ▁newly ▁independent ▁country ▁would ▁be ▁considered ▁as ▁a ▁new ▁state ▁which ▁would ▁have ▁to ▁negoti ate ▁with ▁the ▁EU ▁to ▁re join , ▁though ▁EU ▁exper ts ▁also ▁suggested ▁trans itional ▁arrang ements ▁and ▁an ▁exped ited ▁process ▁could ▁apply . ▁Political ▁consider ations ▁are ▁likely ▁to ▁have ▁a ▁significant ▁influence ▁on ▁the ▁process ; ▁in ▁the ▁case ▁of ▁Catal onia , ▁for ▁example , ▁other ▁EU ▁member ▁states ▁may ▁have ▁an ▁interest ▁in ▁blocking ▁an ▁independent ▁Catal onia ' s ▁EU ▁membership ▁in ▁order ▁to ▁d eter ▁independence ▁movements ▁within ▁their ▁own ▁borders . ▁ ▁Leg al ▁effect ▁on ▁EU ▁citizens hip ▁ ▁Cit iz ens hip ▁of ▁the ▁European ▁Union ▁is ▁dependent ▁on ▁citizens hip ▁( n ational ity ) ▁of ▁a ▁member ▁state , ▁and ▁citizens hip ▁remains ▁a ▁compet ence ▁entirely ▁v ested ▁with ▁the ▁member ▁states