I have not enough imagination to come up with a scenario where making a sandwich would create concern that it might obstruct an investigation. But obstruction is defined by intent and outcome, not the exact means. Abstractions like this are common and necessary in law. So, in your example you'd still be guilty.
Make and leave a sandwich on your counter in case the investigators are similar to the ones who busted up Afroman's house, and you hope that being satiated will make them less diligent.
This actually seems like a halfway good analogy to this case. You're intending to obstruct the investigators, but only if they engage in their own illegality - stealing your sandwich or prosecuting based on political speech.
The "and outcome" is my point. It has to actually be something that could be a problem. Similar to how it's not attempted murder to cast a magic spell intending to kill someone with it, no matter how sincerely you believe in the magic.
Okay but in this case, the act, if successful, would have the outcome that it prevents recovery of critical evidence in a homicide, so yes that would count as obstruction. It didn't, of course, because the plan was foiled, but that's not relevant.
(With that said, I agree that 30 years is excessive, even under the heuristic that it should be a greater penalty than the crime it supported.)
