Some writers, editors, and dictionaries don’t care about the interchangeable use of due to and because of. Is that, perhaps, because of a lack of grammar information, or is that, perhaps, due to a lack of grammar information? Others (and I count myself in this category) adhere to the established rules for their respective uses because it’s otherwise ungrammatical; that is, it’s an English grammar error.
Use due to when you can replace it with caused by; this usually occurs when a form of the verb to be (is, am, was, were, are) is used by itself.
- Some would say that the rising price of gas is due to corporate greed.
Is is a form of to be that is being used by itself, and caused by would make as much sense as due to, as in Some would say that the rising price of gas is caused by corporate greed.
Use because of after other verbs; you can usually substitute on account of for because of to test it.
- Some would say that the price of gas is rising because of corporate greed.
Here, we do not have a form of to be by itself; even though we have is, we have it with the verb rising. If we substitute on account of for because of, the sentence does, indeed, make sense, as in …the price of gas is rising on account of corporate greed.
Here are another couple of examples:
- The meeting started (verb other than to be) 30 minutes late because of a late delivery of doughnuts.
- The postponement was (form of the verb to be by itself) due to a late delivery of doughnuts.
Sherry
Everything Language and Grammar 