Peine forte et dureIn the common law legal system, formerly a defendant who refused to plead would be subjected to peine forte et dure (Law French for 'strong and hard punishment'), having stones placed upon their chest until they either entered a plea or died.
The common law courts originally took a very limited view of their own jurisdiction. They imagined themselves to lack jurisdiction over a defendant until he had voluntarily submitted to it by entering a plea seeking judgment from the court. Obviously, a criminal justice system that only punished those who volunteered for punishment was unworkable; this was the means chosen to coerce them.
Many defendants charged with capital offences nonetheless refused to plea, since thereby they would escape forfeiture of property, and their heirs would still inherit their estate; but if the defendant plead guilty and was executed, their heirs would inherit nothing, their property escheating to the Crown. But today in all common law jurisdictions a defendant who refuses to enter a plea has a plea of not guilty entered for them on their behalf.