If you want to know if a man is of the true Irish blood there is one infallible test.

The method can also be faulted by reference to that infallible test of relevance, 'so what?'.

Used rarely and with reluctance this was, she had found, the infallible test.

In other words, the apparently infallible test performed before the team's departure from 1975 had been worthless.

That is the one and sole and infallible test of all ideas that will ever be presented to you.

"What is this infallible test?"

Don't you see that it gives us an infallible test for blood stains.

It was an infallible test; as he brought the pencil lead near the formica table top, the jittering of his hand made a tick-tick-tick rhythm.

Both of you know that this isn't an infallible test, but it's a harmless ritual and a way to establish rapport.

The blood doesn't show any acid traces, and that's the one infallible test.