Counter-warrants are an advanced strategy. Here are three general templates you can use to set yours apart:

Relevance

The more specific a warrant is, the better. Suppose you’re discussing the effectiveness of food aid by the US. One piece of evidence says: “US food aid is effective.” The other says: “Food aid is ineffective.” All else being equal, the evidence specific to the US should win out. In policy, read your opponent’s conflicting evidence carefully to see if it is being used too aggressively.
 

Qualifications

Sources are a big deal. First, many debaters in two of the leagues I coach think it’s okay to skip sources. It’s not. It’s unethical, it skips the whole point of having evidence (because we still have to take it 100% on the debater’s word), and it misses a quick, free credibility boost.

If a source isn’t read – or if it doesn’t contain qualifications (“According to Sean Smith …”) jump on it. Tell the judge that it doesn’t count as evidence until sources are provided. Having them back at the table doesn’t count.

Whenever you present evidence, talk up your sources. It’s not just “Colin Butler of the University of Canberra,” it’s “The award-winning Professor Colin Butler is the founder of the Benevolent Organization for Development, Health, and Insight. He has been published hundreds of times and is a leading expert on globalization and health. Here’s what he has to say.” Speak of your sources with great reverence. You don’t want any room for disagreement. A high schooler can disagree with the first source, but disagreeing with the second just looks silly – even if that disagreement is backed up by average evidence.
 

Scope

If the affirmative application is about an obscure government agency and the negative application is about a technology that is used daily by billions of people, it’s easy to see which to use. Scope is quantitative. The more people are impacted, or the larger the area, or the longer it lasts, the bigger the scope.

Here’s an example: Stoa LDers sometimes point to Israeli success to defend preemptive warfare. The negative replies by talking about the horrors that would occur if other nations adopted pro-preemption strategies. You do the math:

Affirmative warrant: A small country successfully used small-scale preemptive warfare. 

Negative counter-warrant: World superpowers, armed with the deadliest weapons in human history, aggressively launching attacks at other nations that are connected via military alliance to the rest of the globe. 

The fact that preemptive can work with a handful of tiny nations – or sometimes avoid larger conflicts – isn’t enough to keep up with the scope of the other side of the picture.

Final note: If your opponent can reasonably contest your counter-warrant, look for another way to win that issue. Your counter-warrant should be so obviously superior that there is no contest.