Public domain and previous user

Public domain and previous user

When discussing intellectual property, it is crucial to comprehend the concept of public domain and its potential hindrance to new technology protection. Additionally, it is necessary to understand the implications of using third-party protected technology, known as the previous user, before filing a patent application. This article examines the effects of public domain and the previous user on patent law in Brazil.

What is public domain?

Public domain refers to the condition in which an invention has no longer individual property rights and is free from any restrictions regarding its sale, manufacture, use, import, export, and production.

On this topic, the doctrine states that:

“Entry into the public domain in each legal system is unconditional, universal and definitive; creation becomes common to all, and everyone has the right to maintain it in communion, preventing singular appropriation. (page 50 of the book Industrial Creations, Business Secrets and Unfair Competition, (Barbosa, Ahlert, Labrunie, Moro, & Jabur, 2007))”

In this section of the doctrine, it is evident that once an invention enters the public domain, it can no longer remain in the private domain. Therefore, any patent applications for inventions identical or similar to those publicly disclosed cannot be granted, as they fail to meet the criteria of novelty and inventive step.

Therefore, it can be concluded that any publicly disclosed invention is considered part of the prior art. This means that the invention can be manufactured, sold, used, imported, exported, or made by any person or company interested in it.


However, not all disclosure implies entry into the public domain. In the case of publication of a patent application, despite having been disclosed, the invention is part of the private domain of the patent application holder. But, it is worth noting that once the patente term expires, the invention becomes part of the public domain.

Another exception arises if an inventor discloses information about an invention within the 12 months before filing a patent application. This time frame is called the grace period. In essence, even when an inventor makes public the details of their invention, they retain the right to file a patent application without the disclosed information becoming public domain.

What is previous user?

A previous user refers to anyone who had already used a technology before a patent was filed for that technology. Such a user has the right to continue using that invention, whether it’s a process or a product. Article 45 of the law guarantees this right.

“Art. 45. A person who in good faith, prior to the date of filing or of priority of a patent application, exploits its object in this country, shall be guaranteed without onus the right to continue the exploitation, in the previous form and conditions.”
“1º. The right conferred under the terms of this Article can only be ceded by transfer or leasing, together with the business of the undertaking, or the part thereof that has direct relation with the exploitation of the subject matter of the patent.”
“2º. The right to which this Article refers shall not be guaranteed to a person who had knowledge of the subject of the patent due to disclosure under the terms of Article 12, provided that the application was filed within 1 (one) year from the disclosure.”

Taking into account art. 45 of Law 9279/96, it can be concluded that if a person used a technology prior to its patent being filed, they can continue to do so as long as they do not alter the form or condition of the exploitation. The purpose of defining the exploration as occurring in the “previous condition” is to prevent any expansion or change in the product or process level previously produced. For instance, a previous user cannot extend the exploration territory.

The exception to article 45 is outlined in section 2 of the same article. It applies when the material was disclosed by the inventor or applicant to a previous user before submitting the patent. As a result, there is no prior user right, and the inventor is still protected under the grace period.

Does previous user necessarily characterize public domain?

While it may seem logical to assume that a previous user’s existence nullifies novelty and inventive step, this notion fails to consider the possibility of a previous user utilizing the invention under an industrial secret regime. In such cases, where there is no public disclosure, the invention does not fall into the public domain or previous art category. This is elaborated on in paragraph 1 of article 11:

“§ 1º. The state of the art comprises everything made accessible to the public before the date of filing of a patent application, by written or oral description, by use or any other means, in Brazil or abroad, without prejudice to the provisions of Article s 12, 16 and 17.”

In light of the excerpt above, it can be concluded that undisclosed information is not considered as part of the prior art. Thus, industrial secrets are not included in the prior art.


Considering this article, we can see a significant correlation between patent rights and the concepts of public domain and previous user. It is crucial to take into account the prerequisites for an invention to enter the public domain and the previous user’s rights. Understanding these aspects is crucial in determining whether your invention is patentable and for a previous user to refrain from violating the patent rights of others.