▁may ▁be ▁sub po ena ed ▁( iss ued ▁with ▁a ▁witness ▁summ ons ), ▁although ▁this ▁is ▁normally ▁a ▁form ality ▁to ▁avoid ▁court ▁date ▁cl ash es . ▁ ▁Scotland ▁ ▁In ▁Sc ots ▁Law , ▁Dav ie ▁v ▁Mag istr ates ▁of ▁Edinburgh ▁( 1 9 5 3 ) ▁provides ▁authority ▁that ▁where ▁a ▁witness ▁has ▁particular ▁knowledge ▁or ▁skills ▁in ▁an ▁area ▁being ▁exam ined ▁by ▁the ▁court , ▁and ▁has ▁been ▁called ▁to ▁court ▁in ▁order ▁to ▁elaborate ▁on ▁that ▁area ▁for ▁the ▁benefit ▁of ▁the ▁court , ▁that ▁witness ▁may ▁give ▁evidence ▁of ▁his / her ▁opinion ▁on ▁that ▁area . ▁ ▁Compar ing ▁Ex pert ▁Wit ness ▁law ▁in ▁the ▁UK ▁and ▁the ▁US ▁ ▁Similar ities ▁between ▁UK ▁and ▁US ▁Ex pert ▁Wit ness ▁Law ▁ ▁The ▁purpose ▁behind ▁the ▁use ▁of ▁expert ▁witness es ▁▁▁ ▁United ▁Kingdom : ▁Ex pert ▁evidence ▁is ▁to ▁furn ish ▁the ▁Judge ▁or ▁j ury ▁with ▁necessary ▁scientific ▁criteria ▁for ▁testing ▁the ▁accuracy ▁of ▁their ▁conclus ions ▁ ▁United ▁States : ▁Ex pert ▁evidence ▁is ▁adm iss ible ▁on ▁the ▁basis ▁that ▁the ▁knowledge ▁will ▁help ▁the ▁tri er ▁of ▁fact ▁to ▁understand ▁the ▁evidence ▁or ▁to ▁determine ▁a ▁fact ▁in ▁issue ▁ ▁Qual ification ▁of ▁Ex pert ▁Wit ness ▁▁▁ ▁United ▁Kingdom : ▁Ex pert ▁witness ▁is ▁qualified ▁to ▁give ▁evidence , ▁where ▁the ▁court ▁itself ▁cannot ▁form ▁an ▁opinion ▁and ▁special ▁study , ▁skill ▁or ▁experience ▁is ▁required ▁for ▁the ▁purpose ▁ ▁United ▁States : ▁An ▁expert