The Green Line, designed to traverse low-income District communities and parts of Prince George's County, has remained largely unbuilt because of a court challenge, neighborhood controversies and shortages of funds.

Under current plans, one section of the line would open in 1989, running from Anacostia to Metro's proposed Shaw and U Street stations in Northwest Washington, and the line would be extended into Prince George's in the early 1990s. But prospects for meeting this timetable are uncertain.

Construction of the line's southeastern branch, which would reach from the Washington Navy Yard through Anacostia to southern Prince George's, has been blocked for more than a year by a federal judge's order in a dispute centering in the county.

The line's northern branch has been entangled in neighborhood controversies stemming from objections among some residents to proposed routes near Rock Creek Cemetery and Fort Totten Park.

Another dispute has arisen in College Park, where the City Council recently objected to a proposed site for a station. In addition, no federal money has been earmarked for building the Green Line's outer sections, which would link U Street with Greenbelt, and Anacostia with southern Prince George's.

Only a short stretch near the line's midsection has been built, including the still-unopened Waterfront station at 4th and M streets SW. The station, which is substantially completed, has been mothballed since the court order was issued in March 1982.

The Green Line would share several stations with the Yellow Line, including three now open. These are L'Enfant Plaza, Archives and Gallery Place. Construction also is expected to start shortly on tunnels connecting Gallery Place with a station at Mount Vernon Square, another stop serving both the Yellow and Green lines.

The court battle over the line's southeastern branch was triggered by the transit authority's decision in 1980 to alter its plans by endorsing a new route terminating near Rosecroft Raceway. The switch was quickly challenged in court by Prince George's residents and business operators who preferred Metrminus near Branch Avenue.

In a rulinssued in U.S. District Court in Baltimore, Judge Norman P. Ramsey prohibited further construction ofted improperly by failing to provide adequate notice to Prince George's and District residents that a change in the route was being considered when hearings were held in 1977.

Aducted, Metro's lawyers have not persuaded Ramsey to rescind his order. Advocates of the Branch Avenue plan have bolstered their legal challwith new allegations of improper conduct by the transit agency. If Ramsey does not modify his ruling, a trial may be scheduled for year, ensuring further delays in the line's construction.

The disputes in Northwest and Northeast Washington have stemmed from fears among some re of disruption caused by the line's construction. Metro officials are studying 37 possible routes for the rail line between Columbia Heightsrt Totten, with hearings expected later this year. A court challenge by Rock Creek Cemetery and other groups is considered possible.

In atrict officials and residents have objected to plans for an elevated section of the line east of the Fort Totten station and have urged thatnel be dug. Metro officials have opposed this proposal, contending that a tunnel would increase the line's cost by $100 million.

In College Park, the City Council has or a shift in the station's proposed site to a vacant tract on the city's southern edge. The council's plan has stirred opposition, however, in other Prince George's communities ane county government has not endorsed the city's plan.