Sorry, @ChrisInEdmonton, respectfully I have to disagree with you -- Although about hiring a lawyer, the question directs specifically with taxes.
@PropositionJoe, some details about what local/country and types of returns would be helpful, as well as why the need for a lawyer? In general, a lawyer is needed to represent you in US Tax courts, an accountant/CPA or Enrolled agent will not be permitted to represent you. That having been said, if you need to be represented IN TAX COURT, it is imperative (stress IMPERATIVE!!) that your attorney be a TAX attorney in the specific field you are dealing with (i.e. if a problem with payroll taxes, then a payroll tax attorney). Just because the attorney has a law degree and is a member of the BAR, does not mean they have a clue (beyond the most very basic) about taxes or dealing with the IRS. It is not unusual (and very highly recommended) that the attorney have an accounting degree. Your state BAR may list attorney specialties. Ask any prospects specifically how often and under what circumstances they've dealt with the tax entity (such as: US-> IRS, Calif. -> FTB).
If only about filing (US, State) taxes (even if your taxes are very complicated -- businesses, divorce, Cap Gains/Losses, etc.), or prior years, most if not all can be handled with a competent CPA or EA, without the nee However, if you have even a whiff that this could head to a TAX court, do not pass GO, go directly to a TAX attorney.
I am not an attorney, CPA or EA, consider these my opinions only. Consult a professional.
If as you say the taxes are not complicated, you may be able to resolve this without a CPA or EA, if you feel confident in dealing with the IRS. You can locate the tax forms for prior tax years are at irs.gov (usually the your state tax board can provide prior state tax forms, if needed, too.). Obviously, make sure you can justify all of your entries. There are going to be multiple penalties and interest fees, so leave those boxes to the agency to assess. Then contact and advise the IRS of the coming returns. You'll be advised of the penalties and interest, but you will also receive a notice of specific fees in a couple of weeks. Once you receive the notice, contact the IRS again, and ask to discuss a payment plan -- you'll have to jump through some additional hoops (that's detailing personal income and expenses), but it's pretty straight-forward. Think negotiation, but the IRS does want as much of the tax it can reasonably expect to receive over the next five years... if you're income has decreased to the point they can not reasonably expect to receive the back tax, they have the ability to reduce the tax, penalties and/or fees (but don't expect them to 'rollover').