During this council, the teaching on transubstantiation—a doctrine of the Catholic Church which describes in precise scholastic language the transformation in which the bread and wine offered in the sacrament of the Eucharist becomes the actual blood and body of Christ—was defined.
Lateran IV stands as the high-water mark of the medieval papacy. Its political and ecclesiastical decisions endured down to the Council of Trent while modern historiography has deemed it the most significant papal assembly of the Later Middle Ages. The Fourth Lateran Council was the largest and most representative of the medieval councils to that date.
In summoning the bishops to a general council, Innocent III emphasized that reforms must be made in the Church and that a new crusade to the Holy Land must be launched. He also reminded them that it was not appropriate that episcopal retinue include birds and hunting dogs.
The agenda laid out in Vineam domini Sabaoth included reform of the Church, the stamping out of heresy, establishing peace and liberty, and calling for a new crusade. During this council, the doctrine of transubstantiation—a doctrine which describes the method by which the bread and wine offered in the sacrament of the Eucharist becomes the actual blood and body of Christ—was infallibly defined. The scholarly consensus is that the constitutions were drafted by Innocent III himself.
In secular matters, the Council confirmed the elevation of Frederick II as Holy Roman Emperor.
There were violent scenes between the partisans of Simon de Montfort among the French bishops and those of the Count of Toulouse. Raymond VI of Toulouse, his son (afterwards Raymond VII), and Raymond-Roger of Foix attended the Council to dispute the threatened confiscation of their territories; Bishop Foulques and Guy de Montfort (brother of Simon de Montfort) argued in favour of the confiscation. All of Raymond VI's lands were confiscated, save Provence, which was kept in trust to be restored to his son, Raymond VII. Pierre-Bermond of Sauve's claim to Toulouse was rejected, and Toulouse was awarded to de Montfort; the lordship of Melgueil was separated from Toulouse and entrusted to the bishops of Maguelonne.
Canon 3: Procedure and penalties against heretics and their protectors. If those suspected of heresy should neglect to prove themselves innocent, they are excommunicated. If they continue in the excommunication for twelve months they are to be condemned as heretics. Princes are to be admonished to swear that they will banish all whom the Church points out as heretics. This canon mandates that those pointed by the Church as heretics shall be expelled by the secular authorities or they will be excommunicated if failing to do so.
Canon 4: Exhortation to the Greeks to reunite with the Roman Church.
Order and discipline
Canon 5: Proclamation of the papal primacy recognized by all antiquity. After the pope, primacy is attributed to the patriarchs in the following order: Constantinople, Alexandria, Antioch, Jerusalem.
Canon 6: Provincial councils must be held annually for the reform of morals, especially those of the clergy. This was to ensure that the canons adopted would be implemented.
Canon 7: Set down the responsibility of the bishops for the reform of their subjects.
Canon 13: A good deal of Innocent III's time had been spent judging complaints of bishops against the religious orders. This canon forbade the establishment of new religious orders. Those who wished to found a new house were to choose an existing approved rule. It is this canon that led Saint Dominic to adopt the Rule of St. Augustine.
Canon 18: Clerics may neither pronounce nor execute a sentence of death. Nor may they act as judges in extreme criminal cases, or take part in matters connected with judicial tests and ordeals. This last prohibition, since it removed the one thing that gave the ordeal its value, was the beginning of the end of trial by ordeal.
Canon 19: Household goods must not be stored in churches unless there be an urgent necessity. Churches, church vessels, and the like must be kept clean.
Canon 20: Ordering that the Chrism and the Eucharist to be kept under lock and key, with a three month suspension for leaving it out carelessly, and worse if 'anything unspeakable' were to happen to it.
Canon 21, the rule "Omnis utriusque sexus", which commands every Christian who has reached the years of discretion to confess all his, or her, sins at least once a year to his, or her, own priest. This canon did no more than confirm earlier legislation and custom, although it is sometimes incorrectly quoted as commanding the use of sacramental confession for the first time. In actuality the confession came into existence over a long period of time. However, this was the first time that it took the shape of the Christian confessional as we know it today.
Canon 22: Before prescribing for the sick, physicians shall be bound under pain of exclusion from the Church, to exhort their patients to call in a priest, and thus provide for their spiritual welfare.
Appointments and elections
Canons 23–30 regulate ecclesiastical elections and the collation (assignment) of benefices.
Canon 26: Ecclesiastical procedure.
Canon 35: Defendants must not appeal without good cause before sentence is given; if they do, they are to be charged expenses.
Canon 36: Judges may revoke comminatory and interlocutory sentences and proceed with the case.
Relations with the secular power
Canon 43: Clerics should not take oaths of fealty to laymen without lawful cause.
Canon 44: Lay princes should not usurp the rights of churches.
Canon 47: Excommunication may be imposed only after warning in the presence of suitable witnesses and for manifest and reasonable cause.
Canon 49: Excommunication is to be neither imposed nor lifted for payment.
Canons 50–52: There had been kings of France and Castile who had repudiated their wives and "remarried" with serious public consequences. Marriage, impediments of relationship, publication of banns were addressed in Canon 50.
Canon 53: The council condemned those who had their property cultivated by others (non-Christians) in order to avoid tithes.
Canon 54: Tithe payments have priority over all other taxes and dues.
Canon 57: Gave precise instructions on the interpretation of the privilege of celebrating religious services during interdict, enjoyed by some orders.
Canon 63: No fees are to be exacted for the consecration of bishops, the blessing of abbots or the ordination of clerics.
Canon 64: Monks and nuns may not require payment for entry into the religious life.
Regulations relating to Jews and Muslims
Canon 67: Jews may not charge extortionate interest.
Canon 68: Jews and Muslims shall wear a special dress to enable them to be distinguished from Christians so that no Christian shall come to marry them ignorant of who they are. 
Canon 69: Declares Jews disqualified from holding public offices, incorporating into ecclesiastical law a decree of the Holy Christian Empire.
Canon 70: Takes measures to prevent converted Jews from returning to their former belief.
In addition, it threatened excommunication to those who supplied ships, arms, and other war materials to the Saracens.
Effective application of the decrees varied according to local conditions and customs.
James Carroll has described the clothing regulations as "the precursor of the infamous yellow badge". He emphasises the key role of the Council in effecting major changes in Jewish-Catholic relations, and quotes the Swiss priest Hans Küng who wrote:
It was not the riots in connection with the First Crusade in 1096, but this council which fundamentally changed the situation of the Jews, both legally and theologically. Because the Jews were ‘servants of sin,’ it was concluded that they should now be the servants of Christian princes. So now, in Constitution 68 of the council, for the first time a special form of dress was directly prescribed for Jews, which would isolate them: they were banned from taking public office, forbidden to go out during Holy Week, and had a compulsory tax imposed on them, to be paid to the local Christian clergy.
^ ab"The Albigensian Crusade and heresy", Bernard Hamilton, The New Cambridge Medieval History: Volume 5, c.1198–c.1300, ed. Rosamond McKitterick, David Abulafia (Cambridge University Press, 1999), 169.
^Beginning Firmiter credimus et simpliciter confitemur,text in Henricius Denzinger and Iohannes Bapt. Umberg, SJ (1937), Enchiridion Symbolorum, Definitionum et Declarationum de Rebus Fidei et Morum, Freiburg im Breisgau: Herder, Canon 1, # 428–430, pp. 199–200.
^Of importance is the fact that Joachim himself was never condemned as a heretic by the Church; rather, the ideas and movement surrounding him were condemned. Joachim the man was held in high regard during his lifetime.
^At that time this referred at least chiefly to the parish priest. However, its actual meaning is what is now called a "priest with faculties", specifically the authority to hear the respective penitent's confession. This authority is now more broadly distributed among priests.
^ abAbercrombie, N., Hill, S., & Turner, B. S. (1986). Sovereign individuals of capitalism. London: Allen & Unwin.