obstruction
/əbˈstrʌkʃən/
noun
plural -tions
[count] :something that blocks something else and makes it difficult for things to move through
the condition of being blocked so that things cannot move through easily [noncount]
[noncount] :the act of making it difficult for something to happen or move forward
Obstruction of justice is the crime of trying to stop police from learning the truth about something.