Why is there a 'statute of limitation' for sex crimes?

Question

As I understand it, there is no statute of limitations for murder: in contrast sex crimes (rape) have time limits to prosecute.

Is there a line of reasoning to decide which classes of crime have a limited window for prosecution?

Answer 1

There are great jurisdiction by jurisdiction differences in the statutes of limitations that apply to crimes.

Some jurisdictions have no statute of limitations for any serious crime (e.g. Canada and if I recall correctly Virginia).

Others have statutes of limitations for almost all serious crimes other than murder (e.g. Colorado).

Where there is a statute of limitations, the primary issue is that the ability of the prosecution and defense to secure reliable evidence that will allow a jury to enter an accurate verdict.

This potential to conduct a fair trial can be compromised by a delay in pressing charges. Alibi witnesses can die or disappear to someplace that they can't be located, the location of the alleged crime can change in ways pertinent to proof, memories of witnesses in general can fade. Records or correspondence that could show intent can be destroyed. This is particularly a burden for an innocent criminal defendant who did not know that he or she needed to prepare a defense and gather evidence to respond to criminal charges.

Some states toll statutes of limitations during a period of a victims minority or incapacity when brining charges may not be feasible.

Other states have a long statute of limitations in rape cases where there is DNA evidence available that can conclusively tie a defendant to the scene of the crime (lack of consent would still have to be established), but a shorter statute of limitations in other rape cases.

Murder and fraud are the most common offenses to lack a statute of limitations, in the first case, because it is considered the most serious crime and because the victim is unable to report the crime, and in the latter case, because fraud, by its nature and by the perpetrator's design, may go undiscovered for very long periods of time.

Is there a line of reasoning to decide which classes of crime have a limited window for prosecution?

While I've given some examples of the considerations that apply, ultimately, this is a legislative and political decision and not a legal one. You can't determine by reason alone which classes of crimes will have a limited window for prosecution. Different legislative bodies make different decisions on the same issues at different times and in different places.