Despite the absence of express or necessarily implied authority in the Criminal Code, it is well-established at common law that the Attorney General has the authority to withdraw an information or charge prior to plea. 

R. v. Dick, 1968 CanLII 231 (ON SC), [1968] 2 O.R. 351 (H.C.J.), at p. 359; R. v. Osborne (1975), 11 N.B.R. (2d) 48 (S.C.(A.D.)), at paras. 17 and 30; R. v. Blasko, [1975] O.J. No. 1239 (H.C.J.), at paras. 5 and 6; Re Forrester and The Queen (1976), 33 C.C.C. (2d) 221 (Alta. S.C.(T.D.)), at pp. 223-5.

Leave of the presiding judge is required to withdraw an information or charge after plea[FN].

The authority of the Attorney General to withdraw an information or charge in advance of plea, however, is wide.  No authority limits the right of an agent of the Attorney General to withdraw an information to only those informations laid by law enforcement officials.  The Attorney General may, therefore, withdraw an information which has been laid by a private informant.

See R. v. McHale, 2010 ONCA 361, at para. 33.

While the business of withdrawals is strictly that of the Attorney General and its agents, and is subject to very limited review by the courts (R. v. McHale, 2010 ONCA 361, at para. 36), the courts have commented that the Crown may not be permitted to withdraw charges if its decision to withdraw is based on an oblique or inappropriate motive, such as an attempt to circumvent an adverse ruling by the court.

See R. v. Dick; R. v. Scheller 32 C.C.C. 273;  but see R. v. Scott, [1990] 3 SCR 979, 1990 CanLII 27 (SCC), where the Crown stayed the proceedings in order to protect the identity of an informer (and later recommenced proceedings) avoiding the circuitous route of offering no further evidence and then having to appeal the inevitable acquittal.

Staying the proceeding v. withdrawing a charge

The entry of a stay is a statutory administrative discretion given to the Attorney-General or counsel instructed by it (see s.579 of Criminal Code).
The terms “stay of proceedings” and “withdraw a charge” are not synonymous. When a charge has been withdrawn, there is no charge on record, and in order to continue the prosecution a new charge would have to be laid. Withdrawing a charge has the effect of ending the proceedings. 

When a stay has been entered however, the Attorney General can, up to one year after the entry of the stay of proceedings, recommence the proceedings without having to lay a new charge.  

See section 579(1), Criminal Code; Regina v. Dick, 1968 CanLII 231 (ON SC).

Entering a stay of proceedings has the effect merely of suspending the proceedings, at least initially.  If the proceedings are not recommenced within the one-year period, they are deemed never to have been commenced.

It is well understood that the common law allows the Crown to withdraw an information or any of the particular charges that comprise it. However, section 579 of the Criminal Code refers only to the Attorney General or its counsel staying a “proceeding”. While judicial stays (found at common law) may be in respect of an individual charge, it would appear that statute-based Crown stays must be in respect of the entire proceeding.

[FN1] An accused is put in jeopardy once a plea is entered before a court of competent jurisdiction:  R. v. Peterson, [1982] S.C.J. 75.