page_title: Roller derby
section_title: Rules
hierarchical_section_title: Roller derby / Rules
caption_attribution_description: English: Then-Charm City All Star (Baltimore, MD) blocker Joy Collision vs. a Rhode Island Riveter (Providence, RI) jammer, fastest woman in Rhode Island, Hysterica!.
context_page_description: Roller derby is a roller skating contact sport played by two teams of fifteen members. Roller derby is played by approximately 1,250 amateur leagues worldwide, mostly inside the United States.
  Game play consists of a series of short scrimmages in which both teams designate a jammer and four blockers to skate counter-clockwise around a track. The jammer scores points by lapping members of the opposing team. The teams attempt to hinder the opposing jammer while assisting their own jammer—in effect, playing both offense and defense simultaneously.
context_section_description: Contemporary roller derby has a basic set of rules, with variations reflecting the interests of a governing body's  member leagues. The summary below is based on the rules of the Women's Flat Track Derby Association (WFTDA). In March 2010, Derby News Network claimed that more than 98% of roller derby competitions were conducted under WFTDA rules. For example, members of the United Kingdom Roller Derby Association are required to play by WFTDA rules, while members of the former Canadian Women's Roller Derby Association were encouraged to join the WFTDA.
caption: A Charm City All Stars (Baltimore, Maryland) blocker vs. a Rhode Island Riveter (Providence, Rhode Island) jammer
exif: {"Image Make": "NIKON CORPORATION", "Image Model": "NIKON D80", "Image Orientation": "Horizontal (normal)", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Ver.1.01", "Image DateTime": "2008:06:21 14:57:41", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "216", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "300", "Thumbnail YResolution": "300", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "26940", "Thumbnail JPEGInterchangeFormatLength": "9040", "Thumbnail YCbCrPositioning": "Co-sited", "EXIF ExposureTime": "1/200", "EXIF FNumber": "4", "EXIF ExposureProgram": "Manual", "EXIF ISOSpeedRatings": "1000", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2008:06:21 14:57:41", "EXIF DateTimeDigitized": "2008:06:21 14:57:41", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "2", "EXIF ExposureBiasValue": "1/3", "EXIF MaxApertureValue": "4", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash fired, auto mode, return light detected", "EXIF FocalLength": "55", "EXIF SubSecTime": "70", "EXIF SubSecTimeOriginal": "70", "EXIF SubSecTimeDigitized": "70", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3872", "EXIF ExifImageLength": "2592", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "26800", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CVAPattern": "[0, 2, 0, 2, 1, 2, 0, 1]", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Manual Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF FocalLengthIn35mmFilm": "82", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "High gain up", "EXIF Contrast": "Normal", "EXIF Saturation": "Hard", "EXIF Sharpness": "Normal", "EXIF SubjectDistanceRange": "0"}