"But it is common ground that the contract
imposed an implied obligation on each party to
do all that was reasonably necessary to secure
performance of the contract. As Lord Blackburn
said in Mackay v Dick (1881) 6 App Cas 251 at
263:
'as a general rule . . . where in a
written contract it appears that both
parties have agreed that something shall
be done, which cannot effect-ually be done
unless both concur in doing it, the
construction of the contract is that each
agrees to do all that is necessary to be
done on his part for the carrying out of
that thing, though there may be no express
words to that effect.'
It is not to be thought that this rule of
construction is confined to the imposition of an
obligation on one contracting party to
co-operate in doing all that is necessary to be
done for the performance by the other party of
his obligations under the contract. As Griffith
CJ said in Butt v McDonald (1896) 7 QLJ 68
at 70-71:
'It is a general rule applicable to every
contract that each party agrees, by
implication, to do all such things as are
necessary on his part to enable the other
party to have the benefit of the contract.'
It is easy to imply a duty to cooperate in the
doing of acts which are necessary to the
performance by the parties or by one of the
parties of fundamental obligations under the
contract. It is not quite so easy to make the
implication when the acts in question are
necessary to entitle the other contracting party
to a benefit under the contract but are not
essential to the performance of that party's
obligations and are not fundamental to the
contract. Then the question arises whether the
contract imposes a duty to cooperate on the
first party or whether it leaves him at liberty
to decide for himself whether the acts shall be
done, even if the consequence of his decision is
to disentitle the other party to a benefit. In
such a case, the correct interpretation of the
contract depends, as it seems to me, not so much
on the application of the general rule of
construction as on the intention of the parties
as manifested by the contract itself."