▁witness ▁is ▁qualified ▁by ▁knowledge , ▁skill , ▁experience ▁or ▁education ▁ ▁Ad miss ibility ▁of ▁Ev idence ▁▁▁ ▁United ▁Kingdom : ▁Ex pert ▁evidence ▁must ▁be ▁provided ▁in ▁as ▁much ▁detail ▁as ▁possible ▁in - order ▁to ▁conv ince ▁the ▁judge ▁that ▁the ▁expert ' s ▁opinions ▁are ▁well ▁founded ▁ ▁United ▁States : ▁Ex pert ▁testim ony ▁to ▁be ▁based ▁on ▁sufficient ▁facts , ▁data ▁or ▁products ▁of ▁a ▁cred ible ▁source ▁of ▁test ▁and ▁tried ▁principles ▁and ▁methods ▁ ▁D iffer ences ▁Between ▁UK ▁and ▁US ▁Ex pert ▁Wit ness ▁Law ▁ ▁Con duct ▁of ▁Ex pert ▁Wit ness ▁▁▁ ▁United ▁Kingdom : ▁Ex pert ' s ▁“ d ut ies ▁to ▁the ▁Court ▁override ▁any ▁oblig ation ▁to ▁the ▁person ▁from ▁whom ▁they ▁have ▁received ▁instructions ▁or ▁have ▁been ▁paid ▁by ” ▁ ▁United ▁States : ▁Ex pert ' s ▁duty ▁is ▁not ▁formally ▁defined ▁under ▁the ▁Federal ▁R ules ▁of ▁Civil ▁Pro cedure ▁/ E v idence ▁ ▁De pos itions ▁▁▁ ▁United ▁Kingdom : ▁Ex pert ▁evidence ▁is ▁exam ined ▁before ▁the ▁Judge ▁( or ▁Ar bitr ator ) ▁ ▁United ▁States : ▁Ex pert ▁evidence ▁can ▁be ▁comp elled ▁to ▁de position ▁ ▁Ult imate ▁Iss ues ▁▁▁ ▁United ▁Kingdom : ▁Ex pert ▁opinion ▁on ▁ult imate ▁issue ▁is ▁not ▁adm iss ible ▁ ▁United ▁States : ▁Ex pert ▁opinion ▁on ▁ult imate ▁issue ▁is ▁adm iss ible ▁ ▁See ▁also ▁▁ ▁Amb ush ▁defence ▁ ▁Da ub ert ▁standard ▁and ▁Da ub ert ▁v .