Landfrieden

A Landfrieden or Landfriede (Latin: "constitutio pacis", "pax instituta" or "pax jurata") was, under medieval law of the Holy Roman Empire, a contractual waiver by rulers of specified territories of the use of (actually legitimate) force to assert their own legal claims. This especially affected the right of feuding. 
Scope.
"Landfrieden" agreements formed the political basis for pursuing claims without resorting to the private use of violence. They also often regulated the jurisdiction and thus allowed the settlement of disputes through judgements based on a common set of rules. 
Offences or violations of the public peace were liable to severe punishment. For example, objects or buildings (such as churches, homes, mills, agricultural implements, bridges, and especially imperial roads) and people (priests, pilgrims, merchants, women, even farmers, hunters and fishermen in carrying out their work) could be placed under protection. The "Landfrieden" created a type of martial law, as well as special courts, the "Landfriedensgerichte".
Development.
In the High Middle Ages from the 11th century onwards, the "Landfrieden" movement strove to extend the so-called Peace and Truce of God ("Gottesfrieden"). The first imperial "Landfriede" was established by Emperor Henry IV in 1103 for a term of four years and was known as the First Imperial Peace of Mainz ("Erster Mainzer Reichslandfriede"). It followed the Mainz Peace and Truce of God ("Mainzer Gottesfrieden") which he had already proclaimed in 1085. 
In 1152 Frederick Barbarossa proclaimed the Great Imperial Peace ("Großer Reichslandfrieden"), which extended to the whole Empire. This was an act of constitution and brought into effect a time-limited alliance of ruling princes. It was established in 1186 that a feud had to be announced in feud letter issued three days in advance. Originating from the law schools in Bologna and Pavia, the concepts of medieval Roman law ("Corpus Iuris Civilis") started to dominate the legal profession under Barbarossa's rule.
The most important Imperial Peace of Mainz ("Mainzer Reichslandfrieden"), announced by Emperor Frederick II at the Imperial Diet of 1235, was more like a legal decree and had less of the character of an alliance. Already in 1231, Frederick had issued the Constitutions of Melfi, a book of codified law and inquisitorial system applying to his Kingdom of Sicily. The Mainz "Landfriede", now applicable for an indefinite period of time, was a constitutional act and became one of the basic laws that applied to the whole Empire. For the first time this document was bilingually drafted, i.e. written in both Latin and Middle High German. 
Subsequently, numerous regional and local "Landfrieden" alliances, such as city federations arose during the 13th and 14th centuries. The 1235 Peace of Mainz was superseded by the Perpetual Public Peace ("Ewiger Landfriede") passed by Maximilian I in 1495, which definitely outlawed any feuds and constituted a permanent "Landfriede" for the Holy Roman Empire, including the establishment of the "Reichskammergericht" (Imperial Chamber Court).
Modern forms.
Up to today a breach of the "Landfrieden" ("Landfriedensbruch") by involvement in violent riots is a criminal offence according to German criminal law (§ 125 StGB) and the Austrian (§ 274 StGB) and Swiss (Art. 260 CH-StGB) equivalents. The preservation of the "Landfrieden" in the sense of public law and order – i.e. the ban on jungle law ("Faustrecht") and frontier justice ("Selbstjustiz") – by giving the state authorities a monopoly on violence, is the basis of all modern legal codes.