The current wave of sexual abuse allegations are (often) about actions that happened a LONG time ago (15+ years). I thought that, due to the long time, these crimes will be time-barred.
Is this true? or can the accused be prosecuted for old crimes?
It obviously varies by jurisdiction, but most jurisdictions I am familiar with have something like a "Statute of Limitations" where crimes cannot be prosecuted after a certain length of time because it was "too long ago".
The logic is firstly that if you prosecute a pensioner for stealing a bottle of beer from a shop when they were 18, the person you are prosecuting is very different from the person that committed the crime.
Secondly, it is very hard to obtain a fair trial after the passing of a long period of time.
As far as I know, all jurisdictions vary the length of time depending on the severity of the crime, and the most serious crimes are never time-limited. Rape usually falls into the category of "never time-limited".
Of course, although murder and rape can be prosecuted after 15+ years, the difficulty of obtaining a fair trial, and of producing evidence from that long ago, means that they may not be.
Finally note that "prosecution" of the accused is often not the primary aim of accusers. They just want to say "this was wrong". Abused individuals often find it very hard to speak out about the abuse; the current scandals have made it that bit easier, by reassuring them that it isn't just them (see the #metoo campaign for example).
This varies considerably by jurisdiction.
Statutes Of Limitation For Criminal Offenses
Canada has not general statute of limitations for indictable offense (i.e. felonies).
Most U.S. states have general statutes of limitations for most of the their crimes which is usually less than fifteen years. But almost none have a statute of limitations for capital murder and many have a smattering of other exceptions. There are a few exceptions to the general rule that toll a criminal statute of limitations (the most notable being that the individual is actively hiding from law enforcement or is residing in a place where the defendant is immune from arrest for the crime), but the exceptions tend to be much more narrow than the tolling exceptions that apply to civil cases.
Many U.S. jurisdictions now no longer have a statute of limitations for at least some rape charges. But, the end of the statute of limitations for rape in many jurisdictions is relatively recent and is sometimes limited to cases where DNA evidence is available. Criminal charges time barred before a change in the law remain time barred.
Almost all of these statutes of limitations are statutes of repose that are counted from the date when the offense actually occurs, whether anyone knows about the offense or not.
Statutes of Limitations For Civil Lawsuits In The United States
Also, while civil lawsuits are subject to statutes of limitation in every U.S. state of which I am aware, the way that those limitations are calculated is often not a statute of repose.
Instead, they are often calculated from the date of discovery of the existence of facts giving rise to a cause of action.
There are subject to tolling for a variety of circumstances, some entirely non-nefarious like minority, disability, and the absence of a defendant from the state, and others that are fault based such as conduct of the defendant preventing or discouraging someone from brining suit.
There are also doctrines that can resurrect an otherwise time barred claim for certain purposes. For example, if someone brings a non-time barred lawsuit against a defendant, the defendant can often bring an otherwise time barred counterclaim against the plaintiff arising from the same facts and circumstances.
The Legal Relevance Of Stale Acts To Contemporary Actions
Finally, of course, there is no statute of limitations in the court of public opinion for purposes of judging someone's character.
Many people are in a position to give an opinion about someone's character a real substantive effect even if it is based upon something that happened a long time ago. These include: voters, clergy, historians, monument decision makers, employers of someone who is an employee at will, potential or current romantic partners, someone conducting a security clearance or background check, a psychiatrist making a diagnosis of a mental health condition, and a board deciding whether to issue a liquor license or casino license.
The main temporal limitations to considering information about someone's bad character involve the issuance of credit reports by a credit reporting agency (where data must be no more than seven years old except for bankruptcies when ten year old data is allowed), and the rules governing when evidence of past bad acts are admissible as evidence of bad character in court to impeach the credibility of a witness.
A lack of Statute of Limitations for Rape is relatively recent (edit: In the U.S.) and the statute still exists for all crimes that occurred before the legislation that changed it went into affect (i.e. if you pass legislation to nullify statute of limitations and it goes into effect on 1/1/90, than any crime from 12/31/89 or prior is still under the last statute of limitations, so there still is a time limit.).
One of the difficult problems is finding evidence as any hard evidence will long be erased by natural decay and any place where you might have found said evidence will similarly have more contamination. With cases that happened decades ago, it could be the case that the technology just wasn't there to process DNA so it was never properly preserved. Remember, O.J. Simpson got off on his murder trial in part because the jury did not fully understand the implication of just what it meant that his DNA was found at the scene of the crime and just how unlikely that event was that it came from someone else.