What is a criminal?
A criminal is a person who has been found guilty by a court of law of having broken a criminal code law. Whether the person has actually broken the law is immaterial. Ideally the court of law tries to determine what actually happened, but what matters in the end is the verdict of 'guilty.'
Intent does not change the criminal label. A criminal is still a criminal whether he is convicted of manslaughter or murder. Intent may reduce the degree of responsibility for the criminal act, in which case a lesser charge may be substituted, resulting in a lesser sentence.
Ignorance of the law does not change the criminal label. However, a person who could not have been reasonably aware that his action would result in breaking the law may be found not guilty, and thus not a criminal. Inability to comprehend the law may also be a reason for being found not guilty.
Inability to distinguish between right and wrong does affect the judgement. A person who is found incapable of discriminating between right and wrong cannot be convicted of a criminal act. This is why young children and the mentally handicapped are not usually prosecuted for criminal acts. Different countries set the age at which a child is able to reason differently, but it usually falls somewhere between 8 and 13 years of age. Similar assumptions apply to those legal systems which try persons under 18 differently from adults, only here the reasoning is that young people have less ability to predict the consequences of their actions. In this case, the slate is often wiped clean once the person attains their majority and has paid any required penalty.
A court of law may also find a person not guilty by reason of insanity. Insanity is the legal distinction of whether a defendant had the ability to distinguish right from wrong at the time of committing the criminal act. Some jurisdictions additionally require that the defendant was not in control of his actions at the time of the crime. It is possible to find a person criminally insane at the time of the crime without judging on current sanity, such as a person who suffered a serious psychotic episode at the time the crime was committed. Those found criminally insane are technically not criminals, but they will be confined in a psychiatric institution and undergo psychiatric treatment until they are determined to no longer be a threat to society or themselves.
Criminals are defined by the laws of the country in which the crime is committed, although the Internet has made defining jurisdiction much more difficult than it used to be. Sometimes a person, returning home to his own country, is arrested and made criminally accountable for his actions in a different country. Other times the laws of one country may be superimposed over the laws of another for the purpose of determining who is and is not a criminal. Captured soldiers are not legally criminals under international law, but those held in the Guantanamo Bay detention camp are held for terrorist actions against the United States, which is against American law. At the same time they have not been charged with any crime, leaving them in a legal gray area where they are neither captured soldiers to be exchanged nor defendants to be given due process. Because of this they are not currently criminals, although some of them may become so.
A hero in one country may be a criminal in another, and a criminal in one country may be a hero in another. One recent example of this is the reporter Muntazer al-Zaidi, who went on trial in Iraq at the beginning of 2009 for assaulting a visiting head of state. While the name is not a household word in the United States, his having thrown his shoes at visiting President George W. Bush is.
Time may also change a hero into a criminal or a criminal into a hero, even in his own country. Neither the law nor the instruments of observation upon which it relies are fixed things, although sometimes they can take a very long time to change. Four hundred and fifty years after Galileo Galilei died under house arrest, condemned by the Roman Catholic Church for heresy, Pope John Paul II declared that the earth was not stationary.
Under church law of the time, scripture was held to be literally true unless an alternate view could be proven beyond a reasonable doubt. It was already known that the moon and planets moved, with the best model of their observed movement being the Ptolemeic pure geocentric planetary model. To prove his proposed heliocentric model beyond a reasonable doubt, Galileo was required to answer Aristotle's original argument that if the earth moved, the stars ought to have observable parallax shifts. Since the stars later turned out to be much further away than originally thought, the equipment of the time was inadequate to demonstrate such parallax. Lacking the crucial piece of evidence that would have allowed him to refute the parallax issue, Galileo was unable to prove his model of the universe beyond a reasonable doubt, and so was branded a heretic and a criminal.