A taxing officer is not to allow:
(a) barrister's fees on a hearing if the barrister:
(i) was not present at the hearing for a substantial amount of the relevant period; or
(ii) did not give substantial assistance in the conduct of the proceeding; and
(b) costs that in the opinion of the taxing officer have been incurred or increased:
(i) through impropriety, unreasonableness or negligence; or
(ii) through overcaution; or
(iii) by agreeing:
(A) special fees to counsel; or
(B) special charges or expenses to witnesses or other persons; or
(iv) by other unnecessary expense.