Finding culprit rows on constraint failure

Any idea if it's possible to get a list of the trouble making rows in an INSERT/UPDATE statement when a constraint test fails?

I'm trying to insert data with an SQLBulkCopy object reading data from a DataTable, and when the constraint fails I have no way of telling which rows caused the issue. The DataTable is quite large, and is actually data from an XML file so I can't really run a SELECT statement against that source to find rows that match the constraint's selection criteria.

Thx!