That's called administrative law. In the federal govt, Congress enacts a broad mandate as a law, and then individual agencies promulgate additional rules on top of that.
As a random example, we benefit as a society when ketchup isn't runny. Congress doesn't want to waste time on this, so the FDA is granted a broad mandate to define foods. The FDA uses this mandate to provide a definition of the viscosity that defines ketchup as well as a way to measure said viscosity.
> The consistency of the finished food is such that its flow is not more than 14 centimeters in 30 seconds at 20 °C when tested in a Bostwick Consistometer
It goes on to define the flow-testing procedure in excruciating detail to prevent loophole abuse.
> Check temperature of mixture and adjust to 20±1 °C. The trough must also be at a temperature close to 20 °C. Adjust end-to-end level of Bostwick Consistometer by means of the spirit level placed in trough of instrument. Side-to-side level may be adjusted by means of the built-in spirit level. Transfer sample to the dry sample chamber of the Bostwick Consistometer. Fill the chamber slightly more than level full, avoiding air bubbles as far as possible. Pass a straight edge across top of chamber starting from the gate end to remove excess product. Release gate of instrument by gradual pressure on lever, holding the instrument down at the same time to prevent its movement as the gate is released. Immediately start the stop watch or interval timer, and after 30 seconds read the maximum distance of flow to the nearest 0.1 centimeter. Clean and dry the instrument and repeat the reading on another portion of sample. Do not wash instrument with hot water if it is to be used immediately for the next determination, as this may result in an increase in temperature of the sample. For highest accuracy, the instrument should be maintained at a temperature of 20±1 °C. If readings vary more than 0.2 centimeter, repeat a third time or until satisfactory agreement is obtained. Report the average of two or more readings, excluding any that appear to be abnormal.
I would recommend opening the federal register and just clicking on random pages. This is what regulators actually create. It's mindnumbingly boring and necessary work that allows you to go to the grocery store, buy a bottle of ketchup, and not have to worry about it slowly being enshittified to save money.
I'm not a lawyer (I just read regulations for fun). My understanding is Congress can still explicitly delegate authority to agencies, but an ambiguity in the law is no longer treated as an implicit delegation of authority.
As an example, the authority to define foods is explicitly delegated by Congress.
> Whenever in the judgment of the Secretary such action will promote honesty and fair dealing in the interest of consumers, he shall promulgate regulations fixing and establishing for any food, under its common or usual name so far as practicable, a reasonable definition and standard of identity, a reasonable standard of quality, or reasonable standards of fill of container.
https://en.wikipedia.org/wiki/United_States_administrative_l...
As a random example, we benefit as a society when ketchup isn't runny. Congress doesn't want to waste time on this, so the FDA is granted a broad mandate to define foods. The FDA uses this mandate to provide a definition of the viscosity that defines ketchup as well as a way to measure said viscosity.
https://www.law.cornell.edu/cfr/text/21/155.194
> The consistency of the finished food is such that its flow is not more than 14 centimeters in 30 seconds at 20 °C when tested in a Bostwick Consistometer
It goes on to define the flow-testing procedure in excruciating detail to prevent loophole abuse.
> Check temperature of mixture and adjust to 20±1 °C. The trough must also be at a temperature close to 20 °C. Adjust end-to-end level of Bostwick Consistometer by means of the spirit level placed in trough of instrument. Side-to-side level may be adjusted by means of the built-in spirit level. Transfer sample to the dry sample chamber of the Bostwick Consistometer. Fill the chamber slightly more than level full, avoiding air bubbles as far as possible. Pass a straight edge across top of chamber starting from the gate end to remove excess product. Release gate of instrument by gradual pressure on lever, holding the instrument down at the same time to prevent its movement as the gate is released. Immediately start the stop watch or interval timer, and after 30 seconds read the maximum distance of flow to the nearest 0.1 centimeter. Clean and dry the instrument and repeat the reading on another portion of sample. Do not wash instrument with hot water if it is to be used immediately for the next determination, as this may result in an increase in temperature of the sample. For highest accuracy, the instrument should be maintained at a temperature of 20±1 °C. If readings vary more than 0.2 centimeter, repeat a third time or until satisfactory agreement is obtained. Report the average of two or more readings, excluding any that appear to be abnormal.
I would recommend opening the federal register and just clicking on random pages. This is what regulators actually create. It's mindnumbingly boring and necessary work that allows you to go to the grocery store, buy a bottle of ketchup, and not have to worry about it slowly being enshittified to save money.