Nature and Structure of the Law of Obligations
We saw in Chapter 10 that Roman law made a distinction between real rights and personal rights,[1936] a distinction that still exists in modern law. A real right can be considered as a right directly in an item of property, the right being thereÂfore enforceable against anyone into whose hands the property comes.
The main example of a real right is ownership, with the result that an owner of property that has been stolen, or otherwise gone astray, can always recover it from even a good faith acquirer.[1937] As we saw in Chapters 13 to 15, however, other real rights were also recognised.Not all rights, though, are real rights. Some rights are enforceable only against a particular person or against particular persons. These rights are called personal rights. A right under a contract is a personal right, for example, and so can only be enforced against the other party to the contract. A person who is not a party to a contract cannot have that contract enforced against him or her.[1938] For example, suppose that I enter into a contract with you to sell you my house. At this point you acquire a personal right against me, by which you can compel me to transfer ownership to you. As we saw in Chapter 11, however, you do not actually become owner until a further act of transfer is carried out.[1939] In the meantime, I am still owner. If I sell the property to someone else instead of you, I can validly transfer ownership to that someone else. I will certainly be in breach of my contract with you, and you will have a remedy against me for that. However, because our conÂtract is enforceable only between us, you will not be able to get the house.
The corollary of the personal right is the obligation of the obliged party to comply with it. In the example in the previous paragraph, you had the right to have ownership transferred to you and I had the obligation to make the transfer.
When we use the term ‘obligation’, we are normally referring specifically to the duty of compliance with the right. For the Romans, though, the term obligatio could refer to this whole relationship between the two parties. Thus, says JustinÂian, an obligation is ‘a legal tie which binds us to the necessity of making some performance’.[1940]For this reason, we refer to the law of personal rights as the law of obligaÂtions. Obligations could arise in different ways and were classified in more than one way.
One important way in which obligations could be classified was according to whether they were part of the civil law (ius civile) or the praetorian law (ius honorarÂium).[1941] Obligations that were part of the civil law were older, and had a tendency to involve a higher degree of formalism and rigidity. By contrast, obligations forming part of the ius honorarium were created by the praetor to supplement or correct the civil law, and often displayed a greater degree of flexibility.
There was also a category of obligations called natural obligations. These were seen as existing according to natural law, but were not legally enforceable. An example was an agreement made by a master to pay money to his slave. The slave could not enforce this, even after being freed from slavery. A natural obligation could, however, have certain legal consequences. If the master in fact paid the money after freeing the slave,[1942] he would be unable to recover it.[1943] This contrasts with the normal position: as we shall see in Chapter 25, normally when money is paid that is not due, that payment can be recovered by the person who made it.[1944] Natural obligations are also known in modern law, although more rarely by that name.[1945]
The most important classification of obligations, though, was according to the kind of conduct that gave rise to it. This way of classifying obligations took some time to develop.
In his Institutes, Gaius said that obligations ‘are divided into two main types: for every obligation arises either from contract or from delict’.[1946] The law of delicts is considered in Chapters 22 to 24, and is concerned with wrongful acts. In other words, I incur an obligation towards you either by entering into an agreement with you or by committing some wrong against you. While, however, that covers the most important cases, it does not cover all of them. Other situations may give rise to an obligation. For example, suppose that I believe that I owe you a debt which, in fact, is not due. I pay you the money that I believe myself to owe. There is no contract here, and no wrongful act has been committed, but the law nonetheless allows me to reclaim the money.[1947] Again, suppose that we are neighbours. While you are on holiday, a storm blows off the tiles from part of your roof. To avoid the rain getting in, I incur expense in carryÂing out temporary repairs to your roof. Once again, there is no contract between us and I have committed no wrong against you. Nonetheless, the law provides a ground on which I can recover my expenses from you.[1948] Elsewhere, therefore, we find Gaius saying that obligations arise ‘from contract, from wrongdoing or by some special right from various types of causes',[1949] with the third category being a miscellaneous one to catch bases of obligation that are not included in either of the others. A further elaboration came in Justinian's Institutes, in which the miscellaneous category is divided into two, according to whether the basis of the obligation was closer to contract or to delict. Obligations arise, says Justinian, ‘from contract, as though from a contract [quasi ex contractu], from wrongdoing or as though from wrongdoing [quasi ex maleficio]'’[1950] This is the structure used in this book. Contracts are dealt with first, in Chapters 18 to 21. Delicts are considered, as has been said, in Chapters 22 to 24. Finally, quasi-contract and quasi-delict, as they are known, are addressed in Chapters 25 and 26 respectively.B.