Krima, i.e. anything that can be laid to our charge, or the subject of a judge's sentence. As 'sentence of guilt,' Rom. 13.2. Christ's krima was written on the cross.
'Judged ourselves' is not the same in Greek as 'judged,' used later in this ver. and in ver. 32, but as 'distinguish the Lord's body,' ver. 29. But 'distinguish' does not imply the active exercise of judgment on our own state, nor a formal scrutiny. Here the force is, If I scrutinize and judge myself, I shall not come under an actual judgment from the Lord's hand. Judging oneself has this force in English, while the Lord's judgment is felt to be a positive result of judgment exercised towards us.