[43] Hence, it was argued that if Ms Fletcher had been entitled to her debt against the defendant before proceedings were brought by the defendant against her and the plaintiff, then, as the proceedings brought by the defendant against her and the plaintiff were for a joint and several obligation, the debt owed by Ms Fletcher to the plaintiff could have been set off against the debt for which the defendant obtained judgment against both of them. It was submitted that the availability of the set-off should not depend upon the accident that judgment had already been obtained. To the contrary, so it was argued, the plaintiff should be entitled to set off against the judgment owed by it the amount owed by the defendant to Ms Fletcher where she was also jointly and severally liable on the same judgment debt as the plaintiff, in order to avoid circuity of action. Counsel submitted that if the plaintiff paid the whole of the judgment debt pursuant to the defendant's demand, it would be entitled to recover contribution from Ms Fletcher for half of the judgment debt paid, but she could recover $11,000 from the defendant. The same result is reached if the plaintiff, availing itself of the set-off available to Ms Fletcher, paid the defendant the difference between the two judgments, and if Ms Fletcher was given the benefit of the set-off on the claim for contribution.
[44] However, this submission demonstrates the reason why one joint and several obligor who is sued alone cannot raise a set-off to which his or her co-obligor is entitled ( Bowyer v Pawson (1881) 6 QBD 540). The reason is that, in a suit so constituted, rights of contribution between the co-obligors cannot be resolved. To take the present case, if the plaintiff were obliged to indemnify Ms Fletcher against her liability under the judgment in favour of the defendant, it would be unjust to allow the plaintiff to rely upon the set-off available to her against the defendant. If that were permitted, she would have to look to the plaintiff, rather than to the defendant, to recover the $11,000 owed to her by the defendant. There is no equity in allowing the plaintiff to distort the true position by taking advantage of a set-off available to her ( Lord v Direct Acceptance Corporation Ltd (in liq) (1993) 32 NSWLR 362 at 369). The position would be different if the co-obligors are both joined in a suit so that a set-off available to one is actually given effect to, and rights of contribution between them can be determined. In the absence of such a suit, the plaintiff is not entitled to avail itself of the set-off available to its co-obligor ( Bowyer v Patterson ).
[45] It is true that in Goodwin v Duggan , Handley and Beazley JJA said that it was possible that if the trustee had been sued alone, she could not have relied on a set-off available only to her co-trustee, rather than categorically stating that position. However, as a matter of principle and authority ( Bowyer v Pawson ), and conformably with the reasons of Powell JA in Goodwin v Duggan , in a suit so constituted, the trustee should not be entitled to raise the set-off available to her co-trustee.
[46] It follows that in an action to set aside the statutory demand, to which the only parties are the plaintiff and the defendant, and in which the set-off available to Ms Fletcher cannot be given effect to, nor rights of contribution between the plaintiff and Ms Fletcher determined, the plaintiff cannot avail itself of the set-off available to Ms Fletcher.
6 In order to avoid what flowed from his Honour's reasons the plaintiff suggests that in this case there was an implied term in the retainer agreement with the solicitors which would allow this to occur. In written submissions the plaintiff submitted:
"In the case of dealing with a solicitor by a husband and wife and their company it is reasonable to imply a term into a retainer that any previous claim for negligence may be offset against fees in respect of that matter."
7 In argument the plaintiff's counsel was asked to specify the term precisely. It was said that the term was "that any amounts may be set off against the solicitor for claims for professional negligence including any previous transactions". Presumably what is intended is that the term would be prefaced by the words "where a solicitor acts for a company and its directors". In submissions on this implied term question the plaintiff referred to Byrne v Australian Airlines Ltd (1995) 185 CLR 410 at 422 where the High Court said the following:
" Implied term