The phrase "a unique and necessary" is correct and usable in written English.
It can be used to describe something that is both one-of-a-kind and essential in a particular context.
Example: "This solution is a unique and necessary approach to solving the problem at hand."
Alternatives: "an essential and distinctive" or "a vital and singular".
(Unless, of course, it is a unique and necessary description).
His voice would be the easiest voice in the world to dismiss – the voice of a very young "mentally challenged" boy from a poor family – yet it would be his voice that held a unique and necessary wisdom.
Trauma centers and the services they provide are a unique and necessary component of our health system.
However, they have indicated to the researchers their belief that research into the effects of common weather conditions on interruptions is a unique and necessary field of study and have promised to continue to be an industry partner providing reliability data for this research.
As the deficiency of Vip or its receptor Vpac2r causes desynchronization among SCN neurons (Aton et al., 2005), this peptide-mediated coupling mechanism is a unique and necessary feature of the SCN in order to generate robust synchronous rhythms.
We hold a completely unique and necessary piece for the symphony of work, play, love and conflict that we are a part of.
While "The Power of Black Self-Love" was only on Emory's Fall 2016 roster, the unique (and necessary) nature of the course make it worth a mention.
Still, "El Museo is an extremely important institution, and its exhibitions, programming and collection are unique and necessary," Deborah Cullen, the director and chief curator of the Miriam & Ira D. Wallach Art Gallery at Columbia University, said by e-mail.
Each book created and sustained its own unique and necessary language.
A.I.G. has historically defended C.V. Starr and Starr International as unique and necessary to the company.
If you are not bringing something unique and necessary to the recovery efforts, don't go.
