A court in Wrocław, southwestern Poland, handed out the jail term after Józef Pinior, a former senator with the opposition Civic Platform party, was found guilty of accepting bribes in exchange for helping businessmen in dealing with government officials.
Pinior pleaded not guilty, arguing that he had received loans rather than bribes.
The verdict is subject to appeal.
The Solidarity trade union played a key role in the collapse of communism in Poland in 1989.
(pk)
Source: PAP/IAR