A D.C. federal court jury convicted District of Columbia defense lawyer John A. Shorter Jr. yesterday of attempting to evade paying $287,600 in income taxes, penalties and interest from 1972 to 1983.

The jury of seven women and five men, which took more than six days to reach its verdict, had convicted Shorter last week of six counts of willful failure to pay income taxes from 1978 to 1983.

Shorter, 58, who has represented clients in some of the city's widely publicized cases, declined to comment on the verdict. He faces a maximum penalty of 11 years in prison and $190,000 in fines, as well as the possibility of disbarment.

U.S. District Judge Harold H. Greene postponed setting a sentencing date until deciding on Shorter's motion for a mistrial based on what he called prejudicial publicity about the case in The Washington Post.

Shorter, who represented himself after dismissing two teams of lawyers, had argued that he was not guilty because of a longtime addiction to gambling that he said compelled him to spend his money to support that habit.

But prosecutors Carol E. Bruce and Darryl W. Jackson contended that Shorter deliberately evaded taxes by living a "cash life style" and hiding his assets in bank accounts under the name of his law partner.

The government charged that Shorter paid only $3,500 of $134,866 he owed in taxes for 1972 to 1983. Penalties and interest brought Shorter's total alleged tax bill for that period to $287,600.

Last June, Shorter withdrew from a plea agreement with the U.S. attorney's office under which he was to admit guilt to the six misdemeanor counts of willful failure to pay taxes from 1978 to 1983 in exchange for the dismissal of the felony tax evasion charge.

A Georgetown University law school graduate, Shorter said he had been a compulsive gambler since age 14. But his gambling defense crumbled after Greene refused to permit him to present expert psychiatric testimony on the issue of "pathological gambling."

Yesterday's conviction marked the most recent of tax-related problems for Shorter. In a 1974 case in Baltimore, Shorter pleaded no contest to one count of failing to file a tax return for 1969. He was placed on probation for five years, fined $2,000, and later suspended for six months from practicing law in the District.

According to the U.S. attorney's office, the government won a civil judgment against Shorter in 1968 for $9,290 in unpaid taxes for 1960 through 1963. In 1977, Shorter was sentenced to one year's probation and fined $21,000 after pleading guilty in D.C. Superior Court to failure to pay District taxes for 1968 and 1970.

Among Shorter's clients have been former D.C. Department of Human Resources director Joseph P. Yeldell, whom Shorter successfully represented against bribery and conspiracy charges involving the lease of a building owned by Washington developer Dominic F. Antonelli Jr., and prominent Washington lawyer William A. Borders Jr., who was convicted on charges of helping funnel a $150,000 bribe to U.S. District Judge Alcee Hastings of Florida.

Last year, he represented convicted cocaine dealer Karen K. Johnson, a former D.C. government employe who was jailed for contempt after refusing to testify before a federal grand jury about allegations of drug use by city workers and others.