But does the Act also have ‘horizontal effect’, that is to ask, does it applybetween two private citizens or between an individual and a business

The concept of 'horizontal effect' refers to the application of certain rights and laws not only in the relationship between individuals and the state (vertical effect), but also in relationships between private parties. Whether a particular act or law has a 'horizontal effect' can depend on the specific legislation and jurisdiction.

In the context of human rights law, for example, some rights are considered to have a 'horizontal effect' and can be invoked in disputes between private parties. This is the case in some jurisdictions for certain fundamental rights, such as the right to privacy or the right to freedom of expression.

However, whether a specific act has a 'horizontal effect' and applies between two private citizens or between an individual and a business would depend on the specific provisions of that act and the interpretation of those provisions by the courts.

Without knowing the specific Act you're referring to, it's difficult to provide a more precise answer. If you could provide more details, I would be able to give a more accurate response.