In order to pass legislation, Congress should be required to attach a testable hypothesis. Money to be spent on drug education? Perhaps that is justified by a prediction that illegal drug use will drop. Money spent on a defense program, a command, control, and communication system for instance? Perhaps it would be justified by a prediction that the number of troops killed by friendly fire would drop. And so on. And posted in a public spot - say a web site - would be the data streaming in to either support or refute the testable hypothesis. An outside group of auditors, statisticians probably, would determine whether the real world events justified continued spending.
It couldn't hurt to force some science on federal spending - something that accounts for more than 20% of our economy. And it might even drive out the ideologues.