The answer to this question depends on the knowledge and background of the client, the seriousness of the matter and how much discretion the decision-maker has to make a positive or negative decision. Canada's immigration bodies say that although applicants have a right to be represented by counsel, no preferential treatment will be given to applicants who have counsel. This is true but it is beside the point. The simple fact that an applicant has a lawyer obviously does not put the application to the front of the line or, in itself, lead to a favourable decision. What a lawyer does is to gather and present evidence in the proper way and present it to the decision-maker along with submissions (arguments) that explain the legal basis for the result that the client wants. Where an immigration officer or tribunal lacks proper or sufficient evidence because an unrepresented applicant has not presented it, there is a big risk that the case will not succeed. Some may think that they can involve a lawyer if something goes wrong, but by that time it may not be possible to fix the problem. Many immigration applications can only be presented once and appeals and reviews of negative decisions are narrow. Being represented by an experienced lawyer means that the proper evidence and submissions will be made in support of the desired outcome. This maximizes the chances of success and can actually save money in the long run, in that it is less likely that money and time will have to be spent on attempts to "fix" a negative decision. This issue is particularly important in the current immigration environment, which is generally restrictive and unforgiving in cases that have not been presented adequately.
Many have said: "I dont need a lawyer because I am telling the truth." This is a misunderstanding of the role of a lawyer. A lawyer does not make up evidence and is prohibited from presenting any false evidence. A lawyer's job is to take real information and present it in a focused and convincing manner with a view to persuading the decision-maker in his or her client's favour.
A reputable lawyer will honestly tell you if you need his or her services or whether you can deal with Immigration on your own in the circumstances of your case. Reputable lawyers are busy helping clients who need them and are not interested in getting involved in situations in which they are not needed.