You are moving the goalposts from "lying" to "being accountable". "I did not lie, so I should walk free" is not, in general, a valid argument in court (but it can work in defamation suits. See http://en.wikipedia.org/wiki/Defamation#Defences)
"You lied, so you should be convicted" isn't true, either. If it were illegal, why do people have to take an oath in court?
Lying may be morally or ethically bad, but in itself, the law is fine with it.
> If it were illegal, why do people have to take an oath in court?
A number of reasons:
* So they can't claim ignorance of the law.
* Because lying in court is such a commonplace that the court system decided a timely reminder would be wise.
* Finally, some statements that are lies can't be prosecuted, for example, anything not material to the issues being discussed. On that basis, the oath stands as a clarification of what is legal and illegal in that specific context.
In spite of the above, lying under oath is very common. It's a rule of thumb that judges will rule against liars rather than try to prosecute them.
> Lying may be morally or ethically bad, but in itself, the law is fine with it.
Yes -- except (two examples) under oath or while filing a police report.
"You lied, so you should be convicted" isn't true, either. If it were illegal, why do people have to take an oath in court?
Lying may be morally or ethically bad, but in itself, the law is fine with it.