Is it permissible to pray behind a lawyer who leads the congregational prayers in the absence of the Imam of the five daily prayers, knowing that his profession might be tainted by suspicions such as concealing the truth and lying?

It is from the Sunnah that the one most knowledgeable of Allah's Book should lead the people in prayer. The lawyer who has memorized Allah's Book is among the most deserving of leading the prayer. Therefore, the profession of law, if it adheres to the Sharia guidelines, is permissible and does not prevent one from leading the prayer. The rule is that anyone whose prayer is valid for himself, his imamate is valid for others.