There will likely always be debate about where to draw lines on animal sentience [“If you were a crustacean, would you feel any pain?” Health, March 11]. What we can agree on, however, is that many animals clearly do experience pain (and pleasure) and can suffer.

Yet our policies and practices fall far short of protecting them. The Humane Methods of Slaughter Act , which requires that animals be rendered insensible to pain before they’re killed, is interpreted by the U.S. Department of Agriculture to exclude chickens , of which we slaughter some 300 every second in the United States . Another exclusion denies rats, mice and birds used in research the basic protections of the Animal Welfare Act.

Our nation’s laws are designed to mitigate suffering, but they fail to cover 90 percent of the animals used for food and experimentation. Science informs ethics, and it is time that what we do catches up with what we know.

Jonathan Balcombe, Washington

The writer is executive director of the Humane Society Institute for Science and Policy.