Should laws require testing certain citizens for evidence of drug use?

There are several options to consider:

Options regarding the extent of testing
Option 1: Prohibit all testing.
Option 2: Permit some testing.
Option 3: Require some testing.

Options regarding the persons to be tested
Option 1: Test all employees.
Option 2: Test all employees who are in any way responsible for the health and safety of people or animals.
Option 3: Test all citizens.
Option 4: Test all those who apply for a driver's license.
Option 5: Test all those who apply for a license to practice a trade or profession.