I assume that you are asking about laws of governing bodies, rather than laws of nature. If so, the various countries of the world have governmental bodies (agencies, departments, ministries, etc.) that have written and enforce to varying degrees of strictness, rules and regulations pertaining to electromagnetic radiation in the radio frequency portion of the electromagnetic spectrum. In the United States, for example, the governing body is the Federal Communications Commission (FCC). Their rules and regulations have the general practical effects of laws in most cases, but are not actually laws.
There are general similarities between the electromagnetic radiation rules and regulations in the various countries, but there also are many variations. Enforcement is rather strict in some places and practically non-existent in others.
Many of the rules and regulations are different for different classes of radio service. For example, in most countries radio amateurs are permitted to use parabolic reflectors of any size to increase the effective radiated power from their transmitters in particular directions, but that isn't true for most other classes of radio service. In the United States, for example, the maximum permitted power of a WiFi transmitter becomes less as the directional focusing power of an antenna used with it increases.
There are FCC rules and regulations in the United States pertaining to human safety when the energy from RF transmitters is concentrated into narrow beams by parabolic reflectors or other means. Those rules vary according to the wavelength of the radiated RF energy.
The short answers to your two questions are that rules and regulations pertaining to them vary from country to country.