Balances and bottles

I served as a juror last week.  It was a civil case, as opposed to a criminal case.  Civil cases and criminal cases have different burdens of proof (in the US system).  In a criminal case, the defendant must be proven guilty beyond a reasonable doubt.  In a civil case, the claims against the defendant must be shown to be more likely true than not true.

In the closing statements, each attorney used a different metaphor for the burden of proof.

The plaintiff's attorney said it was like a balance.  Each side places evidence on the balance, and they are weighed against each other.  If the balance tips just a little way towards the plaintiff, then it meets the burden of proof.

The defendant's attorney said it was like a water bottle that you fill up with evidence.  It starts out empty, and the plaintiff has to fill it up half-way.  Even if the defendant makes no effort to empty that bottle, the plaintiff may still fail to fill it up half-way.

I felt this was an interesting demonstration of how you can totally BS with metaphors.  Which metaphor do you think is more accurate?