In legal contexts, 'technicality' refers to details that could affect the outcome of a case unexpectedly. He was acquitted based on a technicality in the evidence.
Pro Tip 2/3
Positive or Negative
'Technicality' can have a negative connotation, implying an unjust decision based on a rule's fine print. She won by a technicality, though everyone knew she was wrong.
Pro Tip 3/3
Unexpected Importance
Sometimes a 'technicality' seems minor but has major legal implications. On a technicality, the contract was voided.