In determining what a reasonable amount of time is from the time a person is charged with an offence to the first day of trial for the purposes of s. 11(b) of the Charter, the Supreme Court of Canada has set "presumptive" ceilings of 18 months for matters in provincial court and 30 months for matters in superior court. The timelines are referred to as "presumptive" because

A. It is presumed that once those limits have been reached, the court has no option but to dismiss the charges
B. The defence is presumed to accept that it will take longer than those timelines to get to trial
C. It is possible for the prosecutor to present evidence that the delay was not unreasonable even if it goes beyond those time limits
D. The Supreme Court was presuming that more serious offences would reach trial more quickly than less serious offences because of the seriousness of the charges