Русско-англо-русский юридический словарь

aggravating circumstance Accompanying or accessory condition, event, or fact that increases the culpability or liability of an accused. Aggravating circumstances (such as cruelty, recklessness, and malice in causing injury to others) are often considered by the courts in imposing more severe sentence than a typical sentence for similar offenses. (BusinessDictionary.com)

mitigating circumstance Accompanying or accessory condition, event, or fact that (though not constituting a justification or excuse of an offense) may be considered by the courts as reducing the degree of culpability or liability of the accused. Such circumstances may include family or personal situations, and may help in attracting a sentence less severe than a typical sentence for similar offenses. (BusinessDictionary.com)

covering letter or covering note, a letter or note accompanying or following a package or another letter, explaining or confirming its contents. (Useful English Dictionary)

Recently I received a cheque for ?3.75. From the letter accompanying it, it appears to relate to the closing of an account in February 2014. The letter also mentions the opening of an account in August 2014. (Telegraph)