Delay is an element of laches only when unexcused. The existence of facts which excuse delay prevent it, therefore, from amounting to laches. Among the facts which amount in equity to an excuse for delay are infancy of the injured party,1 except where the cause of action accrued during the lifetime of his ancestor who was competent to sue ;2 coverture,3 except where the injury concerns her separate estate with which she is empowered to deal as a feme sole,'1 and insanity or imbecility,5 even if the next friend who sues for the imbecile is himself guilty of laches.6 The fact that the injured party is an Indian in tribal relations has been held not to prevent the doctrine of laches from applying.7