Common Mistakes : Authority

Authority – Noun

BAD: Those who bend the rules are reported to the authority

GOOD: Those who bend the rules are reported to the authorities

BAD: The authority had refused them even their basic civil rights

GOOD: The authorities had refused them even their basic civil rights

To refer in a general way to the officials who make all the important decisions in a country, use the authorities : The authorities estimate that nearly 100,000 immigrants have entered the country illegally

As a countable noun, authority refers to an official group or organization that controls an area or activity:  You can claim housing benefit from your local authority