WASHINGTON — The question of whether flushable wipes – used by potty-training toddlers and people looking beyond traditional toilet paper – are clogging sewer systems will be hashed out in federal court, where a manufacturer has sued the District of Columbia over a new city law regulating when such wipes can be labeled “flushable.” Dallas-based Kimberly-Clark, which manufactures Cottonelle, Scott Naturals and Pull-Ups flushable wipes, alleges that the District law – the first of its kind in the U.S.