Criminal law in Sweden allows both - if no specific reason exist for a psych evaluation of the accused, the person is assumed sane. That's the basic assumption.
If the person doesn't show up, a trial is often postponed once or so, but ultimately, if the accused doesn't show up, the trial can be held anyway if it is considered to be performed satisfactorily despite the absence.
I'm certain regarding in absentia, and doubt the "assume sane, then modify the sentence afterwards if assumption turns out to be wrong" very very much.
To be more precise: it's possible to do a trial in absentia, but only if the maximum sentence is a financial penalty, reprimand, loss of driver's license and so on. Paragraph 232 Criminal Procedure Code (StPO).
