There are more and more drugs becoming available for use (including the newer synthetic varieties such as Fentanyl) and as family lawyers we rely upon testing laboratories to ensure that they are up-to-date with their testing methods. Their reports are invaluable to support (or dispense with) welfare concerns and so can have a real impact on a case.
Sometimes, social services choose to perform regular, repeated oral fluid tests believing it will be cheaper - Courts, social services and many large organisations are all under immense budgetary pressure and taking the cheapest test looks appealing, however a hair test is more efficient and economical. While a single oral fluid test can be used to complement the hair test (checking the few hours or days prior to testing that the hair test will not cover) a hair test will track historic use or abstinence. A hair test every month or three can add crucial detail to the whole picture that would otherwise be missed by relying on one test.