The phrase "cornerstone issue of" is correct and usable in written English.
You can use it when referring to a pivotal issue or topic within a particular area of study or debate. For example, "The cornerstone issue of economics is supply and demand."
The Democratic presidential candidate reiterated the cornerstone issues of his campaign, including promises to address a "rigged economy" and broken criminal justice system.
Guns, economics and even the environment have been cornerstone issues of debate in this country since our constitution was first drafted; they're a bumpy road to travel down, but at least there's a road.
Now we come to Los Angeles Clippers owner Donald T. Sterling; or rather Donald T. Sterling and the NAACP's cornerstone issues of economic and housing discrimination, racial slurs and defamation, and poverty.
This is a cornerstone event of paramount significance.
LETTER TO THE EDITOR from Theodore T. Hayes, re talk-anec "Cornerstone" which appeared in the issue of Sept. 24, 193 "You say that the President….
LETTER TO THE EDITOR from Theodore T. Hayes, re talk-anec "Cornerstone" which appeared in the issue of Sept. 24, 193 "You say that the President made use of an old unused tombstone borrowed from a stonecutter's shop near the Mount Hebron Cemetery during the dedication of the Federal Building.
The New Yorker, October 15, 1938 P. 76 LETTER TO THE EDITOR from Theodore T. Hayes, re talk-anec "Cornerstone" which appeared in the issue of Sept. 24, 193 "You say that the President made use of an old unused tombstone borrowed from a stonecutter's shop near the Mount Hebron Cemetery during the dedication of the Federal Building.
For countries like Yemen and Iraq, environmental initiatives are — way more than an issue of national "conscience" — a cornerstone of development.
The key to appropriate therapy is risk stratification of patients with PE; the assessment of the haemodynamic status is the cornerstone of this issue [ 1].
Trump made veterans' issues a cornerstone of his campaign seizing on the very real and serious scandal of mismanagement at the VA but in practice his administration has focused on privatizing the VA's function, a proposal that is controversial among veterans.
