Is this sentence gramatically correct?

[Miss P]

This is not really an error; it's more a matter of style.

Is it not? I don't think I've ever seen a double semicolon before.

It's fine.  It would be much better with a conjunction (or separated into at least two sentences), but c'est la vie.

OP, it's not going to keep you out of a school. But it's pretty nutty. And I speak as a semicolon devotee (easiest, fastest way to fix a comma splice!).

ITA.

[Eugene Young]

"Adrenaline surged through my body. It was 0530 hours; I sat in the passenger’s seat of the unmarked Dodge; Driving was the office’s second-in-charge."

Note the dual semicolons. I think it's fine.

Second sentence way too long. Short sentences are most effective. it won't keep you out of law school. they only spend about 2 mins on a PS. Plus, once you start law school, you'll find out that you're a bad writer anyway.