Reply To: If your friend eats chalav stam, is it evil…

Joseph
Sherry is an aged/fortified wine, and you have the obvious nesech issue. Once the sherry matures the casks that held the wine are reused by the scotch manufacturers. The scotch is stored in the casks for years, as it imparts flavor and color.
The halachic issue involves bliyos form the sherry. Many hold that the bleyos constitute a significant amount and make the scotch not kosher. From my experience many are not makpid and use any “single malt ” scotch. Many (such as Rav Reisman) speak out against the practice of using any whiskey that doesn’t have a hechsher.