"matter of exception" is a valid phrase used in written English.
You would use it when referring to an exception or something that deviates from the normal or accepted standards. For example, "The mayor's office usually does not accept donations, so this is a matter of exception".
Also, typically, standing in a special relationship, such as a species relationship, is an all-or-nothing feature and not a matter of degree (for an exception, see Quinn 1984).
It might truly be said that books made me, but it was a continuous process, not (with that one exception) a matter of sudden illumination.
At the epicentre, the moderate displacement injury mostly encompassed the grey matter, with the exception of a small rim of spared tissue of the dorsal horn.
With a few exceptions, the subject matter of the etchings of the Lorraine period is less frivolous, and Callot was hardly employed at all by the court at Nancy.
Sometimes, mollifying an irate customer is just a matter of showing them you'll make an exception in their case.
All crisping varieties were greater than 25% dry matter, with the exception of Markies (a variety traditionally regarded as French fry but recently also used for crisping), which was 24.3%, while Russet Burbank was the only non-crisping variety with a dry matter content of greater than 25% (25.2%).
As a matter of fact, biology is made of more exceptions than rules and tools are designed to follow only the rules.
All that matters is whether there is a person or institution that possesses the ability, as a matter of fact, to take a decision on the exception.
Yet whether such instances represent trends or exceptions — or neither — remains a matter of some debate.
Detective work of any kind is largely a matter of persistence and luck, and photo research is no exception.
