Twitter - sized warning about admired formal constraints: did the sonnet really die out because it wasn't democratic enough? (firstthings.com)
Within a set of strict formal constraints, Whitney interweaves opaque and transparent layers of oil paint. (teamgal.com)
Additional constraints on pardons: There are no formal constraints on the president to pardon federal crimes, but there are many informal reasons why a president will not pardon a convicted person. (politics.stackexchange.com)