ðə kɚɹˈɛkt fˈɔːɹm ɪz wɪtʃˈɛvɚɹ ɪz ðə stˈætʃətˌoːɹəli pɹɪskɹˈaɪbd ɔːɹ kˈʌstəmˌɛɹi fˈɔːɹm fɚɹə pɚtˈɪkjʊlɚ kˈoːɹt ænd pɚtˈɪkjʊlɚ dʒˌʊɹɹɪsdˈɪkʃən; ɪn ˈʌðɚ wˈɜːdz, wˈʌn ʃˌʊd nˈɛvɚ ɹˈaɪt "kˈoːɹt ʌv ɐpˈiːl" wˌɛn ðə kˈoːɹt æɾ ˈɪʃuː klˈɪɹli pɹɪfˈɜːz təbi kˈɔːld ˈeɪ "kˈoːɹt ʌv ɐpˈiːlz", ænd vˈaɪs vˈɜːsə.
The correct form is whichever is the statutorily prescribed or customary form for a particular court and particular jurisdiction; in other words, one should never write "court of appeal" when the court at issue clearly prefers to be called a "court of appeals", and vice versa.