R v. Procter (1991), 11 C.R. (4th) 200, 69 C.C.C. (3d) 436 (Man. C.A.) is a useful source for the proposition that the Crown may not refuse stipulations for the purpose of gaining a tactical advantage:
The Criminal Code contains provision enabling an accused person to admit facts for the purpose of dispensing with proof of them. Whilst it is true that such admissions must first be accepted by the Crown (Castellani v. The Queen,  S.C.R. 310), I do not think the Crown is entitled to refuse acceptance where its purpose in doing so is to keep an issue alive artificially. In my opinion, evidence which shows the accused to have committed another crime of moral turpitude should not ordinarily be admitted where its only relevance is to an issue which the accused does not dispute. The accused must, of course, make all necessary admissions. But, if the accused is willing to make them, the Crown should not be allowed to gain entry for prejudicial evidence by refusing to accept the admissions.
(Thanks to Yossi Schochet for pointing out this very helpful case)