The Law of Suspects
On September 17, 1793 the National Convention in Paris passed a decree called the Law of Suspects. The law authorized the immediate arrest of anyone suspected by anyone of being an enemy of the revolution. It was under this law that a citizen could denounce another citizen, leading to their arrest and trial before an often hostile tribunal, driven by a bloodthirsty mob. Appearance before a tribunal was not an automatic death sentence however, except for those nobles who fled from France, priests who had not complied with Civil Authority, and emigres.
The Law of Suspects made several references to suspect persons, listing acts of suspect persons in a manner of degree up to a sixth degree suspect. It provided no definition of penalties for those defined as suspect people; that was left to other decrees and the actions of the tribunals. The Law of Suspects led to old enemies being denounced and brought before the tribunals on a whim. There was no penalty for denouncing someone as a suspect person later found innocent, it was up to the charged to prove their innocence, if they could, rather than the burden of proof being borne by the state.
It must be remembered that at the time of the Reign of Terror France was at war with most of Europe, the Bourbon heir to the throne was in exile with the support of the other European Royal Houses, and there was civil war in France. The Terror and the laws which allowed it to happen were a reaction to the conditions of the day. The Committee of Public Safety (which essentially ran the Terror) had become the executive branch of the French Government for all intents and purposes. Following the overthrow of the more moderate Girondin faction Robespierre and his supporters had control of the Committee.
Because of the war decrees were passed which forced farmers to surrender their crops to the government upon demand. National conscription was passed to provide for the common defense. Draconian enforcement of these laws and an inclination among some of the people to ignore them led to many denunciations. So did the hoarding of some materials and supplies. Hoarding was considered an act of treason against the Revolutionary government and by extension, an act supporting the enemies of the Revolution.
The many laws and decrees put into effect following the Law of Suspects removed many of the liberties for which the French had rebelled in the first place, and perceived threats to the Revolutionary government dominated by Robespierre were dealt with harshly and quickly. Both those who wanted an increase in the Terror to support the war (Hebertists) and those urging moderation (Dantonists) were removed from power, identified as suspect persons, tried, and executed on the guillotine. The Terror and the laws enacted under it remained in force until French military victories rendered them unnecessary in 1794.