As Martin Hyde and others have commented, there’s real confusion in this thread about what people mean by a “technicality”. The real theme of the thread seems to be “people who did IMHO a bad thing and never got punished for it,” not acquittals based on technicalities.
Take the driving example mentioned in the OP, the assault on a pregnant women with intent to cause a miscarriage, and no rape by deception of an unmarried women, mentioned by other posters.
If the law doesn’t prohibit those actions, the fact that the individual doesn’t face a charge isn’t a technicality; that’s a basic principle of a fair legal system: “Nulla poena sine lege” - “no penalty without a law.”
Or, to put it another way:
Outraged Citizen: “I can’t believe that guy is going to get away with X. That’s just wrong! He should be locked up!”
Cautious Lawyer: “Um, you do know that doing X is not an offence? The legislature has never passed a law making doing X a crime.”
Outraged Citizen: “Oh sure, if you want to get technical about it…”
That also applies to the examples given of national leaders who have taken their countries to war. Nations have the legal authority to do things, like going to war or locking up people convicted of crimes, that private individuals cannot do. That in itself can’t be considered a “technicality”, since those leaders have legal authority to do what they have done.
If they exceed that legal authority, yes, they may be liable (e.g. A war crime), but that’s determined on a case-by-case basis, not by a general statement that national leaders have committed crimes and got away on a technicality.
Nor is Nixon a good example. There was no technicality there. The US Constitution gives the President the power to issue pardons for crimes committed against the United States. President Ford chose to use that power to pardon Nixon. A presidential pardon is not a minor technicality: it is the exercise of an important constitutional power.
Nor is the acquittal of O.J. Simpson an example of a technicality. As AK84 alluded to, Simpson was given a full trial; all the evidence known at the time went in; the prosecution did a poor job; the defence did a good job; the jury acquitted. An acquittal on the merits is not a technicality.
Nor is the acquittal of the Bundys an example of a technicality. The prosecution chose to charge them with a conspiracy, and not individual offences. That meant that they were only in jeopardy on the conspiracy charges. Part of the principle of Nulla poena is that the accused is only tried on the actual charges, not on other charges that could have been brought but weren’t.
The jury acquitted because the prosecution hadn’t proved the conspiracy charges on proof beyond a reasonable doubt. That’s not a technicality, but a bedrock principle of a fair trial.
The possibility that the prosecution might have secured a conviction on individual charges is on the prosecution, not an instance of an acquittal on a technicality.