According to CO 11, contracts only require a special form for their validity if the law prescribes such a form. In other words, the principle of freedom of form applies in Swiss contract law. And effectively, all contracts that are important for the digital world can be concluded informally, in particular the purchase contract, service contract, contract for work and license agreement.
The forms provided by law are simple written form, qualified written form and notarisation. Simple written form means that a contract is printed on paper and signed by hand. The latter is possible by means of a qualified digital signature (see Chapter 03.04 Qualified digital signature), e.g. also in PDF format. In the case of qualified written form, for example, individual elements of the contract must be completed by hand, as is the case with a guarantee. Finally, a contract where the law provides for the form of notarisation must be concluded with a notary public, which is the case, for example, with the purchase of land.
Although the law only rarely requires the written form for contracts, in practice the written form is preferable to oral agreements or agreements by implied conduct*, even if such a document is not even signed but only exchanged by e-mail. In the latter case, the e-mail correspondence containing the agreement should always be kept. Of course, digital written agreements can also be signed digitally (see Chapter 04 Qualified digital signature). Written form facilitates proof, prevents misunderstandings and thus prevents legal or even judicial disputes. In written contracts, the parties often reserve the right that any changes to the contract must also be made in writing (reservation of the written form). This contributes, among other things, to an orderly and documented further development of the contractual relationship.
*The so-called «implied conduct» (germ. «konkludentes Verhalten»)” is a (Swiss) legal term. Through implied behaviour, agreements or contracts are concluded without the parties explicitly expressing their will to conclude a contract. They behave in such a way that, according to the principle of good faith (Art. 2 of the Civil Code, CC), it must be assumed that they intend to enter into an agreement to this effect. The conclusion of a purchase contract for a newspaper at a kiosk is usually the result of implied conduct by the parties. The kiosk displays a newspaper with a price attached, the customer takes it and puts it on the counter. The salesperson then bills the newspaper and asks the customer for the price. This is all done without the customer explicitly saying «I would like this newspaper at this price» and without the salesperson explicitly answering «we would be happy to sell you this newspaper at this price».